Carbs

[andy230]

Hello!  Lets blow the dust off this board then will we? 

So if you look here  --> www.team-thumper.blogspot.com

after the engine build, we sorted the brakes, chassis, steering, and some bodywork.

And on Friday there, she ran, making good power once she got going.

On the main jet (a 135) she is great, pulling well, very clean, but only above about 5k.

However, a steady idle is impossible below 4.5k (they were loving me in the paddock!), and no lots of banging and farting under 5 or 5.5k.  Suddenly she comes good, and takes off!

Someone suggested that she was lean on the needle jet, so we raised the needle.  This was even worse, (but still fine on the main) so I presumably I need to go the other way.  However, I can't lower the needle any.  Does that mean a smaller needle jet??  I think I have some, tho is anyone familiar with tuning the CR33 carbs?

Finally, the timing is a bit of a ballpark.  Would alteration of the static timing be likely to cause these effects?

Best change one thing at a time!

cheers

a

[themoudie]

Aye Andy,

Might I suggest a blether with Allens Performance Ltd?

They stock Kehin jets and jet needles.

Cheers, Bill.

[themoudie]

Aye Andy,

Have a read of this URL as well, I know there on about 'kwackers', but there is a reference that those carbies are not the best for tick-over, mid range, just WO!

http://www.kawasakimotorcycle.org/forum/vintage-motorcyle-info/95937-keihin-33mm-cr-roundslide-carb-assy-kz1000-1100-a.html

Hope this improves the picture/understanding

Regards, Bill.

[andy230]

thanks bill,

useful, but I had the same carbs on the 620, and it was lovely, even round town.

I reckon they just need set up right.  Good chance that the wild cam isnt helping things!!

SteveH, any ideas?

a

[Steve Lake]

I reckon a twiddle with the static timin might be worth a go.......prolly best to get a handful of jets and needles and head off for a dyno......have slipstream got a dyno?.....cos martin would be an ideal geezer to have around when you're trying to sort out this type of problem

[Steffan]

No point buggering around with the carb if the timing is iffy. If I am not mistaken the timing with auto advance with higher revs??

So I would suggest getting the time bang on static then dynamic and then worry about the carb settings.

Just my 2p worth.

Steffan

[CHRIS211083]

hi, what carbs are you running and what size are they???

[andy230]

Hi Chris

2x CR33s.  130 mains if I remember correctly

a

[CHRIS211083]

HI, was there a reason for 33's and did you or do you have any problems with them???would you go larger, smaller or stay the same if you had to do it again???cheers chris.

[andy230]

The CR33s:  I had them on my 620SRX (road bike, subsequently raced) and they were great.  It idled, was clean low down, and a very linear curve on the dyno.  they came with that bike.  General thinking states that these are good carbs for the tuned SRX/XT lump.

When I built the 640 motor, they came with some parts, and had also been run on a previous incarnation.

I have never really set them up- in both cases they were just about right (although the last motor is a bit of an unknown quantity)...

I would have no qualms about using them.  The 660 motor seems to favour the FCR flatslide carbs, but the aircooled one appears better on CR33s.  If you can get them, use them on the SRX/XT motor.  Not tried anything else to be honest (bar stock).

However, you'll probably want to speak to Slipstream tuning about setting them up if they're not jetted for your application.

Cheers

andy