Topic: 750 K4 rebuild thread - "Help"

[Clinto]

i figure i should probably name my bike "Help" -- i have very little mechanical experience so please don't laugh too much at all my dumb and obvious questions. and thanks for any help you can give

i bought a K4 off of a guy on craigslist a few months ago. He said he had just rebuilt the motor, new gaskets, new rings, etc... it wasn't pretty but after it started right up with the engine cold and bringing the price down by $200, he convinced me to take it. after closer inspection, i still overpaid but it could have been worse i guess

anyway here it is when i brought it home:



notice the awesome no-key-needed toggle switch


according to PO the engine has 30k on it. after tearing the bike down i've decided to go ahead and do a full engine rebuild as well. he said he had put new gaskets on it but after closer inspection he just used that liquid-gasket crap... probably should have noticed that before i bought the bike.

so after tearing the bike down (scary -- never done this before) and taking the engine out, i took the cam cover off. now I have to clean all this gasket substitute off... any suggestions on what should take it off easily?


also a concern of mine... looks like PO filled one of the screw holes for the breather cover with some sort of jb weld type stuff? the first picture shows broken breather cover (replacement is not too expensive) the second picture shows the screw hole that i cannot tap out


suggestions on what to do here? please don't tell me I need a new cover

[jerry h]

Looks like your going to have to drill the old screw out and then re-tap the hole.   

[Stev-o]

If the motor is in running cond, why rebuild?

[Clinto]

If the motor is in running cond, why rebuild?

i basically just don't trust the engine with as many miles as it has and the PO's work has left much to be desired (he had bolts in place of fuses) so while i have the money and the time, i want to do a full rebuild and hopefully not have to open the engine again for another 30,000+ miles

here's a tentative plan for the bike:

heavy duty cylinder studs
new gaskets
heavy duty cam chain
new engine seals
new primary chain
new points
new electrics / wiring harness (minimal)
new MC, rebuild front brake
rebuild forks
install tappered bearings
maybe new wheels/spokes
CR 29mm carbs, k&n filters

everything else i plan to do is basically cosmetic... i have a finish by date of next May so this gives me about 8 months

[harisuluv]

31k is not a lot of miles for a 750, that is fact.  Now there are variables that can make those 31k very hard but that is another story.  From what I have read the engine starts right up, after I see the phrase "complete engine rebuild" it really sends up a red flag.   

You've seen some of this guy's work but to be honest, guys who do that kind of work don't rebuild motors.  He hasn't gotten very deep into that thing.  You think he would get new piston rings at least and then seal it all up with silicone?  Didn't happen.  The guy who uses a bolt as a fuse is just trying to get by til the next thing needs a fix.

I know you want to feel like you're doing something and getting into that engine sounds like you really got your project going, but often times it is the unwitting downfall of a project when you get "stuck" and then it ends up on craigslist as a basket case.  Where if you had just maybe taken care of what it really NEEDED you would be riding instead of scratching your head.  I'm not saying that you can't do it I'm just saying, point that drive somewhere else--the motor works. 

[Stev-o]

31k is not a lot of miles for a 750, that is fact.  Now there are variables that can make those 31k very hard but that is another story.  From what I have read the engine starts right up, after I see the phrase "complete engine rebuild" it really sends up a red flag.   

My thoughts exactly. I had a 750 w/60K+ miles and still ran good. Aint broke? Dont fix it! If you really want to rebuild a motor, buy a spare, then you can drop in your "hot motor" when wanted/needed.

[Clinto]

31k is not a lot of miles for a 750, that is fact.  Now there are variables that can make those 31k very hard but that is another story.  From what I have read the engine starts right up, after I see the phrase "complete engine rebuild" it really sends up a red flag.   

My thoughts exactly. I had a 750 w/60K+ miles and still ran good. Aint broke? Dont fix it! If you really want to rebuild a motor, buy a spare, then you can drop in your "hot motor" when wanted/needed.

what would you guys suggest i do? just put on new gaskets and seal it back up? i plan on riding across country next spring and i'm worried about the possibility of the engine not being up to snuff. thanks for the input

[Stev-o]

Have you pulled the motor yet?   Check compression to see how that is.

Do you feel comfortable contacting the PO and asking exactly what he "rebuilt"?

[Clinto]

i have pulled the motor... cam cover is off. i've been looking for the past month just for a replacement motor that is clean with low miles but haven't come by one that is close to me. I guess for less than the price of doing a full rebuild i could drive to Conn. to get this one http://forums.sohc4.net/index.php?topic=109814.0

i've thought about contacting the PO and asking him about what all he did but i don't really want to. he was kind of an #$%* to be completely honest :/

[Stev-o]

Is that motor still available? I bought some nice guages from him.

[Clinto]

i don't know i haven't contacted him about it... it is 8.5 hours away from me, i know there has to be one closer but i haven't found it yet

[harisuluv]

If you buy a new motor then what, you're right back in the same situation.  You would actually know less about the internals than the motor that you have right now. 

Check out the head gasket, take a peak at the other gaskets.  If you don't see new ones then you are good, the PO wasn't in there, the original gaskets will probably semi disintegrate when disassembling and they aren't reusable and even if he did try to reuse them there would be telltale signs of copious amounts of some silicone abomination.  Get a new cam cover gasket, if you got a head gasket leak you MAY want to address that while you got it out of the frame, but otherwise after that move on.

To summarize:  PO was a shady douche and said he did x or y.  Turns out he didn't do x or y.  Now you're afraid your motor is suspect when it operates excellent.  If he didn't get into the motor like you were afraid of then there is no reason to get in there yourself, correct?

[Stev-o]

I agree with Haris. The motor probably leaked oil (common) and the PO "rebuilt" it by sealing the cover with silicone. Undo all his "fixes", clean and rebuild the carbs, give it a full tuneup and see where you are.
You will probably be surprised.

[harisuluv]

I agree with Stev-o.

[Stev-o]

I agree with Stev-o.

Ha!  Glad we are on the same page...

[Clinto]

So against the advice of some forum members I've went ahead with the rebuild for my own peace of mind and also for a learning experience... The head and jugs have come off. I'm following along with Hondaman's book so it's been pretty straightforward so far as tearing the engine down.

After I split the cases and get everything apart, I plan on following the "engine inspection" chapter of the book to see what needs replaced/cleaned up/etc..

For now I'd be interested in if you guys have any comments on the condition of the engine so far. Looks like the PO did in fact put new rings on? Can't tell for sure if they're new or not. Should I be worried about the wear on the side of the pistons?


How about the discoloration on the inside of the #4 cylinder wall? None of the other cylinders showed this


Not the best quality, sorry. #2 piston not pictured but it looks about the same as #3 here. Seems like a lot of build up to me


That's about it for now. Gonna try to split the cases this week.. any comments are appreciated

[lucky]

You are definately doing it the right way.

Don't take the PO's word especially after what you have seen.
That cylinder head gasket is the work of a real amateur.

Measure the piston and wall clearance.
Many people stick new rings on pistons that do not fit the cylinder properly.
It may not have many miles but remember it has been 35 years!!
Replace the cam chain tensioner rollers.
Make sure to check the valve wobble in the guides.
DO NOT lap valves with worn out guides.

[Clinto]

Thanks for the advice, lucky. I've actually decided to go with new pistons.. Bought the 1mm overbore pistons from Z1 now i just have to find someone who can bore the cylinders for me which is surprisingly difficult around Pittsburgh

I'm having trouble getting the clutch out. I bought the special tool to but the clutch spins with the nut so it's impossible for me to get enough force behind it to losen it. ANY ADVICE IS APPRECIATED... after about 45 minutes i'm pretty stumped, here is my attempt at a rig to get the nut loose:


Also, one of the four bolts (bottom right in the picture) that hold in the cover that goes over the nut (can't think of an actual name for it) was broken off. Guess i will try to drill it out of there, again, any advice would be great



New pistons, HD studs, HD cam chain, and primary chains came in the mail today.. Just got to get her tore down so I can start putting some of these parts in

[jgmmgood]

Hi.  Have you called Rask up in Evans City?  They do a lot of Brit bike stuff and if they cant punch out your cylinders, they may be able to recommend someone in the area. 
http://raskcycle.com/

[Clinto]

Thanks for the suggestion, I'm waiting on a callback from Ready Ride Motorcycles.. They're pretty close to me so hopefully they're able to do it.

As far as splitting the cases goes, I finally got the clutch nut off with an impact drill. But now I'm stumped.

You see anything I'm not seeing? The 3 bolts and 2 nuts on the top case are out (you can't see at the bottom of this picture)


Hondaman says: "remove the 6mm bolts at the front bottom and then remove the 8mm nuts from the crankshaft bearing supports... ...remove them from their sealing washers"

I'm assuming he's means the 8mm bolts with washers on the bottom of the case that I've taken out? Or does he means something else?

As always, thanks for any help

[mark52]

Now sure concerning your question but I am about to start on my motor so lots of pics and stuff as to your finds can only be helpful. Good Luck

[bjbuchanan]

I don't know if you have found anyone to bore your engine yet but I know atleast around me everybody was charging 85 per cylinder and no negotiation for 4 cylinders. I ultimately got a good used engine but atleast for the price I was looking at I could have shipped it to cyclex and had them bore it to whatever size I wanted for about 70 bucks cheaper. Little bit more peace of mind knowing they do way more hondas than shops I could find no background on

I'm in lower NY so its just food for thought