Author Topic: I'm afraid of rebuilding the engine......help (Read 15131 times)

smack doogle · « **on:** December 23, 2007, 06:26:53 am »

Okay, just started the rebuild, bike is stripped. I've been reading the manual over and over about the engine. I had planned on rebuilding it myself (first rebuild) and I'm not very comfortable rebuilding it myself. I'm very afraid I'll mess it up, there's just so much to it (measure tolerances, check valve clearence, replace bearings, blah, blah blah). The last thing I want to do is rebuild the bike and put in a bad motor just to take it back out. I'm in no hurry but this just seems very overwhelming. Should I look for a running engine and throw that in for the mean time while I go very slowly through this engine? Should I look for a pro to rebuild this engine for me? If I did how much would be reasonable to pay for a rebuild? Yes, I'm trying not to do this by myself in fear of irreversable mistakes. Suggestions? Comments? Am I just bieng a little girl? This is the only thing I'm woried about. All else seems easy enough for me.

lostinthe202 · « **Reply #1 on:** December 23, 2007, 06:39:39 am »

I say you do it. Worst case scenario, you get another engine. But you'll know a lot more than when you started!

Good Luck!

Bodain · « **Reply #2 on:** December 23, 2007, 06:59:53 am »

If you don't do it because your afraid you will mess it up. You will never be able to do it because your afraid you will mess it up, and always be dependant on someone else... In my world it's not so much about the ride. I have lots of rides....

It's about doing it myself.

ekim98 · « **Reply #3 on:** December 23, 2007, 07:01:39 am »

I say go for it. You can surely get someone from here to help you thru the tuff spots. And what you will learn about your engine and the bike will be worth all the headaches.

andy750 · « **Reply #4 on:** December 23, 2007, 07:29:14 am »

You live in Mass right? Well you have Mike Rieck the best CB750 engine builder around living in the same state - he is in Framingham/Ashland area. This is where Im taking my engine in a few weeks. Cant beat him for price and workmanship. When I put my engine back in this time Im going to know it will run the best it can and yes I cant wait for Spring!

Yes I did it myself before (top end and lower end split) but Im just not good enough to get it done (the same way that Mike would) within the timeframe I have.

Anyway good luck if you do try it yourself and there are plenty of people here on the Forum and in MA to help.

cheers
Andy

FunJimmy · « **Reply #5 on:** December 23, 2007, 08:13:06 am »

So far it looks like a 75% vote for doing it yourself and my vote will raise that to 80%.
Engines are cheap and plentiful. Start you rebuild and keep an eye out for a nice back-up engine.
With 30 year old bikes we should all have a second engine anyway. Cheap insurance if you ask me.
I’m looking for a second 550 engine just because the shifting on my current one may be suspect and a second engine cost less than pulling the tranny.

Have fun and learn lots!

smack doogle · « **Reply #6 on:** December 23, 2007, 08:23:43 am »

Yes, I know by not doing it myself I am relying on someone else. It isn't about me doing it for me though. I know I can take it apart and put it back together. I know I can follow instructions. My thing is doing it right the first time (or second or third). I want to be done with the engine and know that when it goes in the bike it'll be perfect. I'd rather have a professional do it right the first time. Everything else will be done by me. I probably will end up doing it but it never hurts to look for alternative methods and routes to take. Ultimately I do want to do this myself. Thanks for the support and encouragement. Guess it's time to start shopping for some feeler gauges and other micrometer and other goodies.
Andy750-info on Mike (point me his way) would be great if for nothing else maybe some coaching.

RRRToolSolutions · « **Reply #7 on:** December 23, 2007, 08:42:59 am »

Amen to doing it yourself. I don't want to scare you, but getting someone else to do it is a gamble in itself. I've been a bike owner for years and there are very few shop mechanics I would trust to rebuild an engine for me.

First, unless they build engines every day and are very familiar with your particular bike's engine, or will take the time to look at the specs and check it once, then twice - you don't want a so-called expert doing one. Most shop mechanics are simply "familiar and not affraid" to do it, but -

1) They nor you can afford to pay them to take extra time to be sure it's all perfect, clean, and torqued to specs.
2) Fewer yet will take the time or care to look up every spec because it's not their bike.

Not all, sure there are some fantastic wrenches out there. From my experience, though - out of 7 or so here locally in various shops - there is only one that I would trust with any bike or any repair I needed. I know this because I've seen his collection of bikes and you never see him angry, throwing things, he never brags, and he's slow as Christmas - but I trust him. I took 16 hours to assemble my CB750, but that's making sure everything was surgically cleaned, platigaugeing the bearings, balancing every moving part to .3 grams - things you'd pay $50-90 per hour for.

Now, go in there and start from the bottom getting everything cleaned. If you have a digital camera (Santa comes in 2 days if not) and start posting your photos and questions. I think it would make a great "how to thread". I for one and I know there are many others will contribute. You've got several pros on here that can do this blind-folded. I got a lot of help from many of them.

DIY!

Regards,
Gordon

nippon · « **Reply #8 on:** December 23, 2007, 01:12:36 pm »

It is very simple.
If you have patience and the passion, nobody can do a better job as the owner of a bike if you do not have two left hands. Why?
You don't have to pay the mechanic's hours.
You don't have to match time lines.
You know what you do and what you have done.
So you can do the best job.
It's fun and you are much more prouder when you drive your self rebuilt engine as when another person did the job.
That's a feeling you can't buy.

With the help on this board, a camera, and reading manuals with torques and the other stuff according to bearings, clearances and so on, it should be an easy job.

nippon.

medic09 · « **Reply #9 on:** December 23, 2007, 01:36:16 pm »

Well, if you didn't have Mike Rieck around the corner, I'd say do it yourself, period!

However, you do have one of the few known quantities available to you. So, a few questions.

How's your cash flow?
Is Mike available when you want him?
Do you have curiosity and a little sense of adventure?
Do you have patience? I think you already said you're in no hurry?
Are there some folks in the area who could help/work with you? Seems to me you might have a few knowledgeable people in your area. A warm garage, free Sundays, and some good beer (no lack of THAT in the greater Boston area!) could make for a very satisfying learning experience.

I would go for the last option if I could. Even the little things I've done so far with the magnanimous help of these forums has left me with some real satisfaction.

754 · « **Reply #10 on:** December 23, 2007, 02:52:32 pm »

If you cant do this engine..then you cant do ANY, and I do mean ANY other bike engine.. they do not come any simpler...

Consider this,
The mechanic wants to make money & do a good job.

You want to do the BEST job, and are willing to take extra time to do this..

Remember to lose this attitude though,

if #### is good, then a lot of it would be better..

its sorta like what they said to do

should be good enough

the tool sort of fits so I used it

I wasnt sure so I guessed..

You have a tremedous resource here.. use it..

smack doogle · « **Reply #11 on:** December 23, 2007, 03:07:05 pm »

Okay, okay, you guys are all very wise and you all are correct, this is a journey I must do myself. I'll definitely be on here and I'll study my manual some more. Thanks for the pep talk, it is much appreciated. After wrestling the engine out of the frame about half an hour ago I realized that if I can pick something up and carry it across the garage than I damn sure can rip it apart and put it together right. Besides, what else do I have to do for the next few months in New England. Rebuilding the carbs, prepping the frame and swingarm, lacing and prepping the wheels, buying new bars, controls, rear shocks, chain and sprockets, side cover, rebuilding master cylinder and caliper, painting/cleaining out tank will only take a few days.........no? Maybe I should space all this out. Thanks again, I'll be here daily and I live on Hanscom AFB, MA so if anyone in the area wants to stop by and see the mess I've made in my garage just let me know. I would love a professional to come by and tell me all that I'm doing wrong, that's how things get done right.

RRRToolSolutions · « **Reply #12 on:** December 23, 2007, 05:07:37 pm »

What engine is this? I see one response suggesting it is a CB750 - is that what you're contempating?

Here are my suggestions -

1) Go to MR Cycles and print you a parts fiche for your bike and engine. These are extremely valuable for logging records of new parts needed and received - that way during assembly you can be sure to use all new parts that you've accumulated.

http://www.mrcycles.com/fiche_select.asp?vcc=Motorcycles&mfg=Honda#SDOWN

2) Loosen the head nuts in the reverse order shown in the shop manual. Turn each a little at a time until all pressure is removed - Do not loosen and remove the nuts full one at the time. That torque sequence is there for a reason.

3) Get ZipLoc bags - quarts and gallons. Put "group" parts together logically. It makes finding them later and knowing what and where each goes.

4) Do not mix the cam towers and parts. They are lettered and have a specific place they fit. A sharpie is a good thing. Remember #1 is the cylinder on your left as you sit on the bike. #4 is of course on your far right. Use those ZipLocs to keep them "matched" up. That Sharpie will write on them perfectly.

5) Do not mix rod bearings. Take each rod assembly apart one at a time!!! The upper and lower fit only one way, but you do not want to mix the bearings for any rod. You may re-use them and you'll need to order replacements based on their size. No- all throws and all bearings are not the same size. The factory would have different sizes from the factory. Some, not all.

6) Do not mix the main bearings - again the factory used difference size bearings during machining and assembly - it's perfectly normal to have 2 even 3 sizes on a new motor. If you're careful and will mark your ZipLocs accordingly, this is as easy as tieing your shoes. It's likely one of things some un-skilled mechanics will over-look.

Remember, you're cases will be upside-down during this step - with the oil filter boss away from you - # 4 will now be on your left. The crank has 5 main bearings - same principal -#1 is to the left when sitting on the bike- turn the motor upside-down it's on your right.

7) Do not attempt to remove the cylinder studs. The cases need to be heated to expand the aluminum before you try to twist these out. Also, removal is "not" normal and not covered in the manual - simply because they should be left in-place and considered "not servicable". People will tell you they've done it, but 1 in 30 attempts will result in a broken stud. These are extremely hard and you will not be able to remove them by drill or easy-out. If you want to upgrade Jay's APE studs, then heat removal steps can be explained.

By looking at the manual, looking at the parts fiche, using slow and logical "grouping" technique with the ZipLocs, and take the time and care to label each, take photos, and notes for later, and the help from many of who've done this - you're going to be fine.

If you don't have a torque wrench - now is the time to get one. Several fasteners need the proper torque. Those crankcase nuts holding the mains, the rod bolts, the many 6mm nuts and bolts through-out, the 8mm cap nuts on the cylinderhead, ect - do not try these without a good wrench. Since you'll need 20 feet pounds on some and 80 inch pounds on others, I suggest the Craftsman Microtorque which is good for 15 "inch pounds" to 250 "inch pounds" (you get feet pounds simply by dividing the those inches by 12) - that wrench will easily handle the 80 inch pounds of almost every single 6mm nut, bolt, and phillips screw on the bike and engine. Most 8mm nuts like the 168 inch pounds, while the two cam 7mm bolts need Blue Loctite and 105 inch pounds.

See, it's easy when you take your time. The investment in a few tools will last you forever.

Regards,
Gordon

upperlake04 · « **Reply #13 on:** December 23, 2007, 05:31:40 pm »

Quote from: Ilbikes on December 23, 2007, 08:42:59 am

You've got several pros on here that can do this blind-folded. I got a lot of help from many of them.
DIY!
Regards,
Gordon

Methinks you are one of them Gordon

nippon · « **Reply #14 on:** December 23, 2007, 11:32:30 pm »

Oh, and marking your parts is very important before you are going to remove them.
So, if you are not replacing the parts with new ones, this makes sure that they come in the same position as they were.
(rocker arms, shifting forks, valves, rocker arm axles, pistons and so on)

Don't mix the valves and the carb parts. Store every valve and valve spring of each intake and outake of every cylinder in single plastic bags. Write a description on the bag and you are save. Same with all parts (pistons, bearings) you could exchange.

smack doogle · « **Reply #15 on:** December 24, 2007, 04:35:09 am »

Great info guys, thanks and yes it is a 73 750. The first thing I bought was ziplocks and a sharpie. I'm still shopping for a torque wrench so all progress is halted till I get one. The wife works at Home Depot (kitchen/bathroom designer so if you need one done she can help out) so that helps. Simple green is $10/gal. there so the carbs will get clean next week. Also, if anyone needs the little O ring gasket for the T bar connecting 1 & 2 and 3 & 4 carbs they have the same size at home depot. When I disconnected my carbs those lil O gaskets were non existent. Each carb is in a ziploc labeled waiting to be taken apart individually and cleaned up. I just finished copying and pasting all the parts fiche and details from your link Ilbikes, thanks for that, it'll come in handy. Do I need anything special to remove bearings? I'm a little worried about the engine, the plugs are still in it but when turning the crank with a wrench it spins very freely (little drag from pistons but you can feel they are smooth moving, no hangups), doesn't feel like there is any compression, any suggestions what to look for?
Thanks again all.

RRRToolSolutions · « **Reply #16 on:** December 24, 2007, 05:24:57 am »

The CB750 is a simple engine - 1 cam, 8 valves, rocker shafts, cam blocks, 1 chain. With plugs in, there should be lots of compression and resistance. You'll know more when you see the rings. Checking your bore against the specs, checking taper, and clearance between piston and bore should be done by someone who knows the tools and process. Here is where a local machine shop (doing motors daily) can help. Just be sure to take them the factory specs - don't expect them to know them. They will let you know if a simple hone and new rings using the original pistons is enough or if you're going to need a bore/hone and new pistons/rings/pins. When I say machine - I'm talking Napa, or other well known shop - it doesn't have to be motorcycle specific. My bore shop builds 10-15 car, street, and drag motors every week. They are 10 times more likely to have the right tools and expertise than your local Honda shop guy.

The rod and main bearings are thin, half circles just like those used in automobiles - referred to as "plain bearings". They are not interchangable. And it's not certain you'll need to replace them, but what is certain - Do Not Mix Them Up. You'll go to any Napa or Autozone and buy plastigauge and check the clearances after getting everything surgically clean. The factory manual will give you the right specs. Removal is simple - just take a small screwdriver and lightly tap (use your palm) the edge of the bearing opposite of the tang to push/raise the tang side above the mating surface, then pull it up with your fingers.

Here's a tip for you - the older, original bearings and materials are actually better than what you get today. If yours check ok - then use them. Buzz says that many racers look for those original bearings. My 9,000 mile 750 checked perfectly and I re-used them after confirming clearances. If the bike has a lot of miles - you should consider a new pair of primary chains and tentioner. New seals for everything.

My # 1 place to get CB750 stuff is www.dynoman.net. You can see his CB750 stuff on-line and Buzz has forgotten more about these than I will ever know. He used to work for Honda America back in the early 70's and then for several race teams - He is in my opinion, the authority on the Honda 750.

The only tricky part or step I felt I needed 3 hands was putting the cylinders on the block. This was made more difficult because much of my chamfer was removed by a big-bore 836 kit - leaving very little cylinder sleeve or chamfer. 1/4 are up while 2/3 are down, so when using ring compressors you're pushing 4 sets of rings into the holes at once. This must be done carefully so as not to break or fold a ring. I've got photos and can loan my Motion Pro compressor tools for a refundable deposit.

Have fun.

Gordon

coolcat2002 · « **Reply #17 on:** December 24, 2007, 06:43:47 am »

I didn't even ask, I just did it and now my place looks like parts warehouse, I'm $1K in the hole, and I still don't have a running engine.

People here sure gave me a whole different response when I tried to do a top end rebuild. They said I was crazy considering I've never heard of a Serdi machine and such. They were right!

My advice is: Don't do it!

I'm serious. Yeah, I know the engine better and, considering how much I pay for grad school, I guess it was a relatively cheap investment for the knowledge you gain. (I pay $100 per lecture hour by the way and I still don't know anything

) If you REALLY want to know engines, get a Norton and work with Whitworth tools, heck, the instructions for their vintage bikes says to dissassemble the entire engine and check after 500 miles.

Another person here commented on how the BMW vintage R-series are a lot easier to work with then our CB because man, 4 cylinders is a lot.

Here's a checklist:

-Garage or Indoor place to work that has no mosquitos, adequate vent & temp.

-Plenty of space for you parts

-Lots of time in your hands, i.e. retired

-Willing to buy tools. Dont' buy cheap Tapping kit & get a Vise-Grip brand not some cheap imitation

-Willing to take pictures and post it on here

If you dont have all of the above, just pay some else to do it. Think about it this way, when your car radiator blows, do you take it to a shop or fix it yourself for the "learning experience" and because it's "fun"?

This forum is good at helping you out but when my head bolt snapped, I pretty much scrapped the engine. Which leads me to another post...

RRRToolSolutions · « **Reply #18 on:** December 24, 2007, 07:01:57 am »

Guys, this ain't rocket science. Save the money by doing the simple stuff yourself and use the savings to have your head ported, a new cam, have fun - what are you in this hobby for anyway? It's too cold to ride up there, no excuses.

cbass*gxc · « **Reply #19 on:** December 24, 2007, 09:05:33 am »

Smack coming from one new guy to another, its not as hard as it seems. I, like you, am very engine illiterate and am still alittle overwhelmed with all this engine stuff, but am just about done rebuilding the top half of my 550 motor. But with everyone and everything here you should have plenty of info and help. Anyways I am sure you could do it. I had to ask a lot of "noob" questions but everyone was very helpful and made it a lot easier. Check some of my topics because there have been a lot of helpful info for people like us.

I am going to get my motor back together and if it doesnt run, well thats what friends are for. Here is some pics of my bike and engine. http://jaypage.com/pics/motorcycle/

Well good luck to you,
Jay

mattcb350f · « **Reply #20 on:** December 24, 2007, 09:23:28 am »

My two... The assembling of the engine can be done easily enough with the aid of the manual and a little know how, but you will still need a machinist to grind the valves and seats, spec the crankshaft, head and cam...

Then there's tracking down all the parts.... This is the stage I'm at now

If I had MRiech around the corner, knowing what I already know now having already started my own build, I'd be giving him a ring.
But if you choose to build your own, just be ready for a lot of searching this forum and the net for parts and you're going to want to find an engine builder anyway to do some machining too.

Matt.

Bob Wessner · « **Reply #21 on:** December 24, 2007, 09:31:58 am »

Ilbikes,

Almost seems a shame to put oil in that and start it. Before you know it, it'll be all dirty in there.

mgmuellner · « **Reply #22 on:** December 24, 2007, 11:18:14 am »

Quote from: coolcat2002 on December 24, 2007, 06:43:47 am

If you dont have all of the above, just pay some else to do it. Think about it this way, when your car radiator blows, do you take it to a shop or fix it yourself for the "learning experience" and because it's "fun"?

I dont do it because it's fun (although it is) but because I'm cheap. It seems that no matter how much money I make it doesnt change. When a radiator blows, I call local junk yards & find someone who has the part - then go get it & put it in my car. Call me stupid, call me cheap - whatever - it's all probably true! Normally I do have a learning experience & it normally has some degree of fun too.

oldfordguy · « **Reply #23 on:** December 25, 2007, 04:50:13 am »

Quote from: mgmuellner on December 24, 2007, 11:18:14 am

I dont do it because it's fun (although it is) but because I'm cheap.

I don't do it because it's fun or because I'm cheap, I do it because I don't trust anyone else! I've seen too many of my friends & family burned by shops, as well as bad work that left the vehicles unsafe to drive. I usually do new parts these days, but in my youth I was a salvage yard scrounger.

My wife took her minivan in to the dealer for a recall on a door handle, and the shop "gave" us a 25 point "free" inspection. They told her it had a leaking rear wheel cylinder (even though the master was full and no fluid had been added) and the rear shoes were almost gone. They wanted like $500 to fix this. They also "found" a coolant leak around the intake manifold (also a full radiator/overflow with no fluid added for at least a year.) They could fix this for the low, low price of $1700! Then they mentioned that the tires also needed rotated, and they would do this for $25. My wife then asked them "you mean you will take the tires/wheels that are sitting on your garage floor, and if I give you $25 you will put them back on in a different place, but if I don't you will put them back where they were?" At this point she told them to put everything back together and let her get the heck out of there. Upon examining the rear brakes, everything was completely dry, and the shoes looked almost new.

Sorry for the rant. This "shop" really pi$$ed me off!

medic09 · « **Reply #24 on:** December 25, 2007, 08:50:05 am »

Quote from: Bob Wessner on December 24, 2007, 09:31:58 am

Ilbikes,

Almost seems a shame to put oil in that and start it. Before you know it, it'll be all dirty in there.

I vote we change his name to Mr. Clean.

Every photo this guy posts is spotless and shiny; immaculate. Gives me a complex...

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Author Topic: I'm afraid of rebuilding the engine......help (Read 15131 times)

upperlake04