Topic: 1977 CB750 K7 Resto-mod, Knoxville

[AintNoEasyWay]

Hmmm....bad fuel, huh?  Too bad no one suggested you dump out the fuel and just put new fuel in there.     

Maybe so, Ron! Wish I could know for sure. I will be putting new fuel in it first thing in the morning. Thanks for your help!

[AintNoEasyWay]

With Ron's help, I managed to fix an increasingly worrisome leak I had coming from my stator/transmission cover. I went ahead & changed the oil for the first time since the engine rebuild.

The leak was just a few drips in the beginning but Saturday afternoon I started up the bike to ride & within seconds I had a real puddle of oil built up. After draining the oil I pulled both covers & found that I had used two stator gaskets instead of one! I also had only fit one of the stator wire grommets to the cover. The other grommet had slid back & I hadn't attached it properly. I went ahead & put non hardening sealant on both grommets & gaskets & got the covers back on, along with new oil.

Been riding a good bit since then & no leak yet. Let's hope it stays that way!

[Restoration Fan]

That's great news, Nate.

I, on the other hand, went the other way.  A buddy showed up yesterday to my house.  We were going to ride together to go & have drinks with an old & dear friend who has ALS (Lou Gehrig's disease) and is in pretty bad shape.

While he was at my house, I showed him the bike he had heard so much about and even cranked it so he could hear her purr.  Well........we left and went for drinks...not getting home for about 3.5 hours and when I got home, I noticed this very strong odor of gasoline in the garage.  I looked over at Stella and there's like 2 gallons of gas on the garage floor.  I had left her on her kick stand with the petcock fully opened and she was weeping gas at a steady drip via the overflow tubes.

Put her up on the center stand after quickly turning off the gas and she's no longer leaking gas but I learned a lesson the hard way about forgetting to turn off the gas. 

[SOHC4 Cafe Racer Fan]

I think EVERYONE has done that (leaving the petcock on), especially those coming from riding modern EFI bikes with no petcock.

[madmtnmotors]

I learned a lesson the hard way about forgetting to turn off the gas. 

Yep, those are the lessons that stick with you. 

Now if I could just remember to turn it back on every time!   

[AintNoEasyWay]

I learned a lesson the hard way about forgetting to turn off the gas. 

Yep, those are the lessons that stick with you. 

Now if I could just remember to turn it back on every time!   

Started down the road the other day & the bike died out on me. I was clueless. I hadn't turned the fuel on! Why is this such a difficult thing to make stick in one's mind? haha.

Ron, glad it wasn't anything more serious though. Hope you're starting to really get to enjoy Stella!

[SOHC4 Cafe Racer Fan]

Yep. I've done that too.

[AintNoEasyWay]

Well, rode the bike a few times in the past two weeks, but I'm back to the same problem again with throttle twists killing the engine. The bike will also only hold idle for about 15 seconds or so then die out if I push in the choke. Before it would at least hold idle until I twisted the throttle. I can only assume that the problems are getting worse or creating others.

So carbs were back off again last night. I went ahead & adjusted all the floats to 12.5 mm down from 14.5 so it's not a question anymore. Pulled the pressed in slow jets & cleaned with carb cleaner, along with the main jets & pilots. All the accel pump nozzles are shooting gas well.

I didn't try firing the bike back up last night after putting everything back on, but I did replace my old spark plugs. I looked down into the cylinders & it looks like my pistons have a lot of grime on them already. I'm worried I've got something wrong & don't want to do serious damage to the rebuilt engine if so. I'm considering taking it to a repair shop outside of Knoxville that does vintage motorcycle repair (same shop that I had set up the valves & do machine work for me) to have them check everything out.

If you guys have any more ideas for what I could try, please let me know!

I am running a MAC 4-1 exhaust with stock air box.
- 110 main jet
- 35 slow jet

I used this kit to rebuild my carbs: http://webhosting.web.com/imagelib/sitebuilder/misc/show_image.html?linkedwidth=actual&linkpath=http://www.cycleonemanufacturing.com/sitebuildercontent/sitebuilderpictures/sir.kh1156nfr.jpg&target=tlx_pic25dr

The clip on my jet needle is set one down from top. Pilot screws 1.5 turns out.

EDIT: Looking here: http://www.salocal.com/sohc/tech/carb/asmpg_mgs/jetgraph.htm, he lists the K7 as having a 115 main jet, but I'm pretty sure my rebuild kit came with 110s so that's what I'm using now. Maybe that's why I've been running so lean!? Any recommendations on what to move up to?

[madmtnmotors]

I don't recall whether this has been addressed, but what condition are the carb to head rubber manifolds in? Are they old and hard and cracked? Sounds like there could be some vacuum leakage.

Also, check the points plate (or Dyna plate, or Pamco plate, etc) and make sure the three attachment screws are tight. The ignition plate is grounded to the engine through the metal backing plate and I have had these rattle loose (or forgot to tighten them  ) and have had the ignition cut out as a result.

[AintNoEasyWay]

I don't recall whether this has been addressed, but what condition are the carb to head rubber manifolds in? Are they old and hard and cracked? Sounds like there could be some vacuum leakage.

Also, check the points plate (or Dyna plate, or Pamco plate, etc) and make sure the three attachment screws are tight. The ignition plate is grounded to the engine through the metal backing plate and I have had these rattle loose (or forgot to tighten them  ) and have had the ignition cut out as a result.

Interesting. I replaced the manifolds from the air box but am still using the original boots between head & carbs. They seem to be in good condition with rubber not cracked or hard at all. I haven't tested for any vacuum leaks. Maybe a good thing to check.

[Restoration Fan]

You know how to check for vacuum leaks, right?

[AintNoEasyWay]

You know how to check for vacuum leaks, right?

I only know how to check it if I can get the bike to hold idle -- by spraying the boots & seeing if RPMs increase. But if the bikes won't hold any idle, I'm not sure of another method.

[madmtnmotors]

Look at the clamps on the boots. If they are stretched/bent then make sure they are not "bottoming out" before getting tight.

[RAFster122s]

It really does not take much of a leak prior to the head on a carb to really throw off the idle. If the boots are a bit too loose/large they will clamp down but leak. Just like a fuel line that's too large will weep or drip.

[AintNoEasyWay]

Look at the clamps on the boots. If they are stretched/bent then make sure they are not "bottoming out" before getting tight.

Also a very good suggestion. Thanks, madmtn. I've replaced 8 of the clamps and they have done great, but the last 4 clamps (between the engine and the manifolds) are original & may have been bent at some point.

[AintNoEasyWay]

Looks like Honda has stopped making the intake boots. Any advice on where to find reliable ones if I end up needing more? I've read on the site where guys had trouble with certain boots because they were cheaply made.

[Bigsam302]

Looks like Honda has stopped making the intake boots. Any advice on where to find reliable ones if I end up needing more? I've read on the site where guys had trouble with certain boots because they were cheaply made.

I got just the place.  Try www.vintagecb750.com.  They are in Canada and they make reproduction boots.  I just picked up a pair and they work well.

Sam

[AintNoEasyWay]

Looks like Honda has stopped making the intake boots. Any advice on where to find reliable ones if I end up needing more? I've read on the site where guys had trouble with certain boots because they were cheaply made.

I got just the place.  Try www.vintagecb750.com.  They are in Canada and they make reproduction boots.  I just picked up a pair and they work well.

Sam

Hmm, looks like they only carry the carb to airbox rubbers.

[Bigsam302]

Looks like Honda has stopped making the intake boots. Any advice on where to find reliable ones if I end up needing more? I've read on the site where guys had trouble with certain boots because they were cheaply made.

I got just the place.  Try www.vintagecb750.com.  They are in Canada and they make reproduction boots.  I just picked up a pair and they work well.

Sam

Hmm, looks like they only carry the carb to airbox rubbers.

You are talking about the rubber intake boots that go from the cylinder head to the carbs, right?  I just checked their website and they do have them for your bike.  They call them carb holders.  I ordered a set from them last month to fit my Mikuni carbs.

[SOHC4 Cafe Racer Fan]

Looks like Honda has stopped making the intake boots. Any advice on where to find reliable ones if I end up needing more? I've read on the site where guys had trouble with certain boots because they were cheaply made.

I got just the place.  Try www.vintagecb750.com.  They are in Canada and they make reproduction boots.  I just picked up a pair and they work well.

Sam

Hmm, looks like they only carry the carb to airbox rubbers.

You are talking about the rubber intake boots that go from the cylinder head to the carbs, right?  I just checked their website and they do have them for your bike.  They call them carb holders.  I ordered a set from them last month to fit my Mikuni carbs.

carburetor/intake/airbox manifolds/rubbers/insulators -- all the same

[Bigsam302]

Looks like Honda has stopped making the intake boots. Any advice on where to find reliable ones if I end up needing more? I've read on the site where guys had trouble with certain boots because they were cheaply made.

I got just the place.  Try www.vintagecb750.com.  They are in Canada and they make reproduction boots.  I just picked up a pair and they work well.

Sam

Hmm, looks like they only carry the carb to airbox rubbers.

You are talking about the rubber intake boots that go from the cylinder head to the carbs, right?  I just checked their website and they do have them for your bike.  They call them carb holders.  I ordered a set from them last month to fit my Mikuni carbs.

carburetor/intake/airbox manifolds/rubbers/insulators -- all the same

That's what I thought 

[madmtnmotors]

carburetor/intake/airbox manifolds/rubbers/insulators -- all the same

The airbox to carb rubbers are different than the carb to head rubbers...

[oldhatt45]

If you look at the fiche, the Carburetor to Head rubbers are called "Insulators".
Honda Part Numbers 16211-300-030 & 16212-300-030
I bought a set not too long ago (maybe a month or so) from JT Marks. 
jtmarks@hvc.rr.com

He is also a member of this forum I believe.
If I recall correctly they price for the set (there are 2 inners Insulator A and 2 outers Insulator B but I may have that reversed ) was $80.00 total for the 4 of them.

Charlie

[AintNoEasyWay]

carburetor/intake/airbox manifolds/rubbers/insulators -- all the same

The airbox to carb rubbers are different than the carb to head rubbers...

Mine are definitely not the same. Maybe they're referring to pre K7 bikes?

If you look at the fiche, the Carburetor to Head rubbers are called "Insulators".
Honda Part Numbers 16211-300-030 & 16212-300-030
I bought a set not too long ago (maybe a month or so) from JT Marks. 
jtmarks@hvc.rr.com

He is also a member of this forum I believe.
If I recall correctly they price for the set (there are 2 inners Insulator A and 2 outers Insulator B but I may have that reversed ) was $80.00 total for the 4 of them.

Charlie

Just what I needed. Thanks Charlie!

[enwri]

What did the plugs you took out look like? when you replaced them on the 16th.
The ones in the previous photos don't look lean, did they look burned clean after riding it around, or sooty.
one of them looked washed clean from unburned fuel.
 aren't they only a few weeks old, they shouldn't need replacing already, or are they the originals from before the rebuild?