Hi Guys

Finally got my bike back from the mechanic. Got it back and it wasn't running so hot. He didn't charge much and it was running better than it did when I sent it to him so I was happy enough.

I know now not to really bother with mechanics. He did however, discover that the floats in my carby were different types and the quick solution was to take the carbs off my newly aquired parts bike and whack them on.

This got the bike running ok, but I knew from the guy I bought my parts bike from, those carbs made it run like a dog.

Mechanic also said the slow jets in the donor carb were too long... so he put the old ones in.

Bike starts ok, idles ok, and revs ok (in neutral - maybe a little slow for the revs to drop back to idle)

As soon as you take off, the bike bogs down unless you slip the clutch like a madman until you get the revs to 6.5k-7k where it powerbands off like a rocket.

Lauching in powerband at every single set of lights gets a bit tiring and also having to ride in powerband is a bit annoying.

I pulled the carbs off today and set the floats to 12mm (they were a bit low) and bumped the main jet size up a bit (my bike has tyga pipes and a drilled airbox - donor bike was stock)

That made it a little better, but still not good.

I know it has power down low because I have ridden it like that. I know it's not awesome power, but currently it's an effort to even get the bike to move below powerband.

I observed a couple of things when I pulled the carbs apart.

In spite of both sets of carbs being TA22B the donor carbs did have longer main jets and shorter slow jets, maybe 3-4mm difference in both cases. The needles in the donor carbs protrude further down into the needle holder.

Also, the powerjet plumbing was all wrong. I have sorted it out now (maybe that what made a difference)

I didn't touch the Air screws because it seemed so good at idle.

Advice time:

What's with the different sized main jet/needle holders?
What length should they be?
What length should the slow jets be?
How much should the needle protrude into the float bowl with the holder off it?
Can you adjust a stock needle?
Should I mess with the airscrews?
Could it be something else (Powervalves/TPS)?

Lastly, I know the X Piece and Y Piece are important, but I was missing the 3 way joint to the airbox. In the interim I have just used a standard three way joint. Is this ok, or do I need a proper one?


Thanks guys

As always you're a big help

By "different length mainjet, needle holder" I presume you mean the emulsion tube?

these are emulsion tubes with mainjets in place (and a pair of needles).

A standard mc21 emulsion tube is 31mm long, an HRC one is around 33mm long (I've not got one to hand).

The different length is for the HRC needle which is also longer, if you ran an HRC needle in it's top clip (i.e. as lean as it can be) on a stock emulsion tube it would jam in the MJ totally at closed throttle.

If you really do mean the main jet then it's just a nasty pattern jet or just not for those carbs at all. I've seen a few with different shape tops and different shape drillings but never any different lengths.

Presuming this is about the same bike as the jet kit thread, lets try to keep the discussion in one place shall we? Or I may try the "merge thread" icon which will almost certainly crash the entire internet.

Actually, disregard that comment there is no merge thread option, only a split thread!
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Last edited by fontyyy on Sun Dec 13, 2009 3:17 pm; edited 1 time in total

Sorry yes, needles and emulsion tubes are longer. I should have taken some photos.

And SJs were shorter.

So now I've got the shorter pair but still the long needles.

How do you get needles out? When I open the top of the carb it's just a metal tab or something in there.

Needle doesn't foul so maybe it's a stock needle moved down (if they can be) or a HRC needle that's up a bit.

Still a bit confused by the whole thing.

If you have longer emulsion tubes should you set your float differently?