Carb swaps for a 550?

I have 2 sets of the standard tk's and both are knackered.

What can I feasably fit? I was thinking gpz CV's, but if there is something better I'd try it!

I'll be running pod's and I'm running a 4-1 with next to no silencing, but it runs poo! I need to adjust the needles but the linkage screws are seized and I know for sure that #1 has damaged idle passages, (on my second set it's #4,) and I need it runnign healthily for the winter as it's my only form of transport!

Cheers,
Jon.

Someone correct me if I am wrong but I think the 550 has a different intake spacing than any other KZ. Plus there are no aftermarket jets on the market for them. You have to drill your own.

We have aftermarket jets over here (i'm in the uk,) as it's been jetted to compensate for the filters and pipes before I had it. The mains are 110 up from 92. I'm sure I have a couple of damaged drillings though, and I'm sure i heard somewhere that gpz550 cv carbs were a direct fit as the cylinder heads are identical?

Jon.

I believe the GPz550 cv carbs will fit. If you need main jets, the small head Keihin mains are a direct fit; they are the same ones fitted to a Harley "big twin" only will be smaller hole sizes.

I don't know what model he has, but the CV carbs won't directly replace the TK22 which are what came on the A,C,D models in the U.S.

The spacing on the manifold's mounting bolts are different. The intake ports on the head are smaller than the CV manifold's bore.

But if you have two sets, and different carbs are knackered on each set, why not combine the carbs from the two sets to make one good set?

Dynojet performance kits and Keyster rebuild kits come with adjustable needles and jets for your carbs (assuming they are the TK22).

Here's the Keyster kit on ebay $13.99.
Part number CK-58-0048
Keyster Part number CK-58-0048 on ebay



Someone posted instruction on how to make the link smaller, but I can't find it. Steve, maybe you could add the instructions to the sticky "forum rules" thread.

Post edited by: loudhvx, at: 2006/09/05 12:03

Ok, went on google and found it.

Like this, but brackets instead of "{" and "}"

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Post edited by: loudhvx, at: 2006/09/05 12:06

yup they're tk 22's. The reason I'm not combining sets is because one lot were sat for 5yrs, the other for god know's how long! Both were full of crap, the spare set more-so. I only bought them to rob the choke slides out as mine were missing the flaps.

It's already been re-jetted, and the Euro models have adjustable needles as standard. Main problem is the screws that hold the throttle shaft in place are mega seized and I don't want to break anything off just to adjust the needles.

I can make adapters, and porting out the head isn't a problem if needs be.

of course I could cheat and buy a gpz head and carbs?

Whats the difference in cams between the two?

Jon.

Crowson_punk wrote:

yup they're tk 22's. The reason I'm not combining sets is because one lot were sat for 5yrs, the other for god know's how long! Both were full of crap, the spare set more-so. I only bought them to rob the choke slides out as mine were missing the flaps.

It's already been re-jetted, and the Euro models have adjustable needles as standard. Main problem is the screws that hold the throttle shaft in place are mega seized and I don't want to break anything off just to adjust the needles.

I can make adapters, and porting out the head isn't a problem if needs be.

of course I could cheat and buy a gpz head and carbs?

Whats the difference in cams between the two?

Jon.

Well the carb center-spacing is the same on the CV's.

You'd have to grind about 3 or 4 mm out of the ID of the port. The port wall will be very thin at the mouth, but it should still work.

Then, on the new CV manifolds, you'd have to find a way to squeeze the bolt hole-centers around 10mm closer together. I'm not sure how you'd do that because you'd be cutting into the manifolds.

Buying an 82 or 83 gpz head and carbs would work, but if you're going to do that much work, use the gpz pistons and cylinders too. The pistons are what give you the higher compression.

The gpz cams (1981, 82/83 are same I believe):
Inlet;
open 31deg BTDC
close 59deg ABDC

exhaust;
open 59deg BBDC
close 31deg ATDC

The A1,A2,A3,B1,B2,C1,C2,C3 cams:
Inlet;
open 20deg BTDC
close 48deg ABDC

exhaust;
open 48deg BBDC
close 20deg ATDC

It's more duration, but there's no mention of lift. I might have a couple C cams I can measure to compare.

EDIT: I measured the cams (just for my own info, but if anyone is interested):

81 or 82, C2 or C3 (LTD). (A (Standard) model should be same):
Cam base circle: 1.106" ~ 1.110"
Cam Height: 1.400" ~ 1.405"
Lift: .290" ~ .300"

81 D (gpz) (82/83 H (gpz) should be same):
Cam base circle: 1.106" ~ 1.110"
Cam Height: 1.430" ~ 1.435"
Lift: .320" ~ .329"

So the gpz clearly has more lift.
The vlaves should all be the same for most of the 550's from 1979 to 1983.


Note: the cams are same intake and exhaust, so they can be swapped. Some exhaust cams have the worm gear for the mechanical tach, but that was deleted after 1981.

The transmissions are the same.

If it was me, I'd just get some used carbs off an LTD (C) model. They're everywhere and the only difference is the main jets.

Post edited by: loudhvx, at: 2006/09/06 12:32

Mine is an ltd!!! well, it's a c2, not a shaft drive ltd. The shaftie's had cv's over here, so If I got hold of those they should be straight swap?

if not, I can make custom manifolds, so does anybody have any other carbs they can recommend?

Jon.