Topic: Setting up keihin VE54 (32mm CV) carbs on a 836

[Old Scrambler]

Very interesting!!! I picked up a '77 F2 with a running motor but low compression.  Turns out the PO installed a standard 836 kit in this black motor.  He said he had difficulty getting good power and speed with the standard carbs and an aftermarket header.  So maybe these carbs will solve my problem!  Or, does anyone want to buy a bike?  Its in Wisconsin.

[cafebob]

another jetting update.

I took JL's advice and put the 115 main back in, running very nice now.  40 slow 115 main. I also tried the 35/115 combo, and it was very flat at 2000-4000 again. I haven't gotten it into 3rd gear yet, but it is running very strong.  I need to get more of the wiring gremlins nailed down.  The head light keeps cutting out so there is at least one loose connection.  But that's what you get when you rewire the whole bike.

I have to saw that the power is a smooth as I have ever felt from a 750.  Most of the 750 I have owned/worked on always had carb problems, and fixing them was a nightmare.  These things are so easy.  No float problems, balancing them is simple, just a dream to work with compared to the stockers.  Mine where 60$ on ebay.  They look like hell, but you can get beautiful sets for 150$ or so.  Nice chrome tops and all that.


I can't say enough good about them. Joy.

[JLeather]

I still think your slides aren't raising properly.  The slow-speed jet should not make a difference in the 2000-4000 rpm range.  But keep at it, eventually you'll get 'em figured out.  Be smarter than the carbs

[cafebob]

well maybe your right....but, we just got a blizzard here so it will be a few days till I can test drive it more.  I did find a stage I dynojet for the carbs. Anyone know what comes in a stage I kit?  I'm not sure if a stage I kit comes with springs....

I am very tempted to try for a FI system.  I found a set of CBR TB's for 75$, and building a megasquirt might be a cool project.  It would make the turbo project much easier.

[Retro Rocket]

Hi Old scrambler, The F2's used different pistons to the regular 750's, if the PO used a "K" series piston kit it would result in lower compression, someone can correct me here but i think the F2's had more dome on the top of the piston to accommodate the different head and valves.

Mick

[cafebob]

you got it right, I used flat top pistons from a 836 kit.  Not sure I of the manufacture, I have a bunch of piston kits in the garage.  I wrote it down somewhere.

The motor has 836 kit, F2 head, F2 Cam, 750 DOHC rods. Compression is around 8.1:1.

[Retro Rocket]

That would probably account for the lower compression then. It was Terry that told me this as i am looking for pistons for a F2 as well.

Mick

[cafebob]

actually I just looked it up and the pistons i used where slightly domed, with small cutouts for the valves.  They are less domed than F2 pistons.  I never identified the manufacture.

Are you trying to make a low compression motor?

[Retro Rocket]

Are you trying to make a low compression motor?

No, i was just inquiring about a piston kit for the F2 and Terry told me not to use a regular 836 kit as the pistons had a smaller dome and would result in lower compression.

Mick

[754]

You dont need a mandrel bender.. just mandrel sections.

 Bring about 150 bux, then spend about 1 or 2 days welding and fitting..

 yeah ...3-400 bux really looks better now..

...................................................................................

I run a Magnum turbo header on my 750.. w/o a turbo.. It is all made out of mandrel bends

[cafebob]

I guess I could try that, but it is going to be a very tight fit.  I want to mount the turbo right above the oil cooler, well in the space above the cooler.  Not a lot of room.  Plus it not something I have done before, and experience tells me that the first time you do something the results are often less than spectacular.  I think I could pull of a 4-2-1, but to go from 4 to 1 in about 3-4 inches of drop is going to be interesting.  I have seen one header from a atp kit that looks close.

here is the link http://forums.dragbike.com/forum_posts.asp?TID=9306&PN=1

That looks like it might work.

@Retro  if you can source domed pistons, you can always use a K head. You have to cap 4 of the cylinder studs, but it is possible.  Hell the K heads are more durable anyway.

[754]

That looks like an RC pipe, the rest looks like ATP.

Maybe ATP used that pipe later, but sure not in the beginning.

Mine has a collector on the left side above Dyno cover. The left pipe is a 180 degree bend, ending against collector.. pipes are unequal length.

[cafebob]

Yup seen those all 4 outlets kind of bend to the right, and come into one pipe. I thought about using one of those and trying to mount the turbo in the usual ATP spot, but it would be a real squeeze, and I'm trying to keep the bike looking as clean as I can.

I found a guy in the local CL that does custom fabing, I have emailed him, maybe I'll get lucky and he will be able to duplicate the RC pipe.

[JLeather]

Yeah, the ATP exhaust pupe is kinda like a log manifold, but it's more complicated than it looks.  It's got a lot of tapers to step the diameter up as it goes right-to-left.  I took it to a local guy to see what it would cost to reproduce and it was even more than having one bent like that RC pipe with more equal-length pipes.  It is a really tight, clean install though, but it's really hard to get on and off the spigots since it doesn't have any flex to it.

[754]

You need an amen frame like JL, then running turbo up & over will be a snap...

[JLeather]

754, that was before I found out the front half of that frame was tweaked (not a surprise considering the amount of crap that had been done to it).  Check out how much room it's got now:



I keep meaning to open a new project thread with pics of all the frame mods and stuff, but I've been a bit busy lately.

[754]

i got mine new, direct from Amen.. and it was out..
had to straighten it myself in the backyard.. that is one stiff neck..