Topic: '78 cb750k with Keihins-how do the @#$% boots seat on the carbs?!?

[Kev Nemo]

OK-I can pop them on the head and sort of seat them by pushing the carbs on, but there is a visible gap on the inner 2/3 connections. If I pop them on the carbs, it's impossible to connect them to the intake holes.

Is there a trick? I'm almost starting to think these are the wrong boots for these carbs.

[City Boy]

Something sounds fishy.They can be buggers to deal with when they get old and hard .They must also be oriented correctly rotationally,if that makes sense,or carbs will not fit up either.I think new  ones are still available,don't cost arm and leg,will make fitting way easier and help avoid intake air leaks which will drive you batty.  Rock On

[eldar]

I think they all have a bend in them so it is important to take your time seating them if you took them all off. I did that once but I am good at eyeballing things and get them back on straight on perfect. Dumb Q but have you made sure or carbs are not being warped by the front plate?

[scondon]

   Boots are numbered 1-4 and attach to the head with the numbers centered on top, #1 on the left intake as your sitting on the bike(sorry if this is stating the obvious, just covering the bases). K7-K8 carbs have a larger diameter than earlier carbs so if you can fit the boot on the carb you probably have the right ones.

   When you say there is a visible gap are you referring to side-to-side spacing issues or that the inner two are not seating all the way up on the carbs?

[duc750f1]

When I tried to refit my carbs on the old intake rubbers, I had the same problem and gave up. Bought a new set from Silvers, clamped them tight onto the cylinder first, then sprayed some Silicon spray on them, and pushed on the bank of carbs fairly easily. It may also help if you try using a heatgun gently to try and soften them up. Hope this helps.

[Kev Nemo]

...When you say there is a visible gap are you referring to side-to-side spacing issues or that the inner two are not seating all the way up on the carbs?

The later-you can see a gap between the boot and carb, as if the were a few cm too short. I'm pretty sure this is the source of my air leak/idle issues and pisses me off that it's so obvious, yet so seemigly hard to remedy.

I'm about to make another go at them-wish me luck!

[scondon]

...When you say there is a visible gap are you referring to side-to-side spacing issues or that the inner two are not seating all the way up on the carbs?

The later-you can see a gap between the boot and carb, as if the were a few cm too short. I'm pretty sure this is the source of my air leak/idle issues and pisses me off that it's so obvious, yet so seemigly hard to remedy.

I'm about to make another go at them-wish me luck!

   I can relate. For some reason these carbs can be a little more stubborn than the earlier ones when it comes to seating 2&3, especially if the boots have gone hard with age. Try some silicon(or grease) like duc7501 suggests and rock the carbs, pressing forward hard on the top then the bottom in the center of the bank. I sit on the seat when doing this so as not to push the bike off the stand.

   Don't give up, they should pop into place

[Sd455]

Two guys, one hand on the fork tubes, the other on the carbs. Both guys pull at the same time, should snap right in.

[lordmoonpie]

Two guys, one hand on the fork tubes, the other on the carbs. Both guys pull at the same time, should snap right in.

Had the same problem with my Keihins ven with brand new boots - solution was to put the boots on the carbs, and then get a tray of boiling water and set the other ends of the boots in that for a minute - quick dry off with the towel and a block of wood under the front wheel and shove them on quickly!! The water has to be steaming hot so it evaporates before doing any nasty damage corrosion wise...

[goon 1492]

I'll one up on that lordmoonpie, mine are as hard a rock and I put mine in the oven at 250 deg.F for about 1-2 minutes, they come out like an over cooked noodle and rush to the bike to install them, and like you said be quick the split second they start to cool down they get super hard again. One thing I was more successful with was installing the #2 & #3 boot onto the carbs, then grab the air box top half and install the #1  into it and then cram them all together REALLY FAST!!!!! , this worked really good but I had to rehearse it three times to make sure it all went as planned. I am not fixing this problem with new ones from hondapartsdirect, they actually have more for these old bikes than I figured.

[lordmoonpie]

ha ha Nice one Goon 1492 - I have visions of you running between oven and bike juggling a set of hot carb boots....LOL 

[Kev Nemo]

got 'em on-greased the boots alittle and *pop*

[goon 1492]

ha ha Nice one Goon 1492 - I have visions of you running between oven and bike juggling a set of hot carb boots....LOL 

Ya almost got it right, I used gloves to save the fingers , it was a mad dash to the bike once I got ready though. LOL
Screamin Hot potatoe! Hot potatoe! All the way