A forum for owners of Yamaha TTR250 trail and enduro bikes!

dlee22 · Senior Member

Has anyone tried a jetting kit?

TTRfan · Super Guru

The Sigma kit seems a bit like snake oil to me Dan confuse

See https://ttr250.activeboard.com/t56757791/sigma6-jet-kit/

In terms of re-jetting your carb, you only need to think about replacing either the pilot or main jet or both.

If Yamaha no longer supply the size of jet you need for your engine and you can't get a used spare then it may be worth considering using carb jet drill bits or buy a kit like this https://www.amazon.co.uk/KESOTO-Carburetor-Motorcycle-Accessories-Replacement/dp/B07H3YHX3T/ref=sr_1_8?keywords=CARBURETOR+JET+DRILLS&qid=1578870294&s=automotive&sr=1-8

Brian

Jeff B · Veteran Member

Jets R Us supplies most of the jets we need. https://www.jetsrus.com/customer_service/shipping_fee_international.html

Maybe the Totally TTR's store can stock a bunch of the commonly used jets.

They currently do not ship to the UK but probably would make an exception for Totally TTR's purchases.

TTRfan · Super Guru

Thanks Jeff - that's useful - I see they sell a 55 pilot which Dan may be keen to try wink

https://www.jetsrus.com/a_jets_by_carburetor_type/a_jet_kits_teikei_selection.html

Sadly the main UK parts supplier now only supplies #147 main and #50 pilot jets

Steve at Totally TTRs does offer a slightly wider range - see http://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectID=1655063&ViewAction=FacetedSearchProducts&SearchString=jet&SearchButton=

impulsive · Member

There are TK jets on ebay for absurdly cheap. From China, of course.

I bought pilots & mains and measured everything with check pins in comparison to the stock jets. Don't have the numbers on hand but can post them later if anyone is interested. All sizes pinned correct in regards to flow orifice.

Overall very close dimensionally and the quality appears surprisingly good. I looked at all jets w/magnification and no burrs or anything suspect.

Yet to run them but just re-jetted/refreshed a carb and it will be back on the bike in a week or so.

Search "TK jet" and they should pop up.

TTRfan · Super Guru

That is really good information - thanks for posting it up biggrin

I am sure that we would be very interested in the numbers if you can post them up please.

Brian

PS Just to show my ignorance - what are "check pins" and where do you get them please? Google wasn't helpful

Cubber · Super Guru

Brian,

Being American this site may be helpful: CLICKY

There again, it may well be a lot of holey baloney biggrin

Martyn

TTRfan · Super Guru

Well done Martyn! Orifice checker eh???

UK version here https://www.ebay.co.uk/itm/143171463392

Does it go down small enough to check pilot jets though?

impulsive · Member

check pins aka gage pins. generally in .001" increments, also come in .0001" sizes.

meyer-black-oxide-class-zz-gage-sets-lib

I work as a machinist and have access to full sets. They go down to literally a hair size above zero.

Will post up numbers this evening.

TTRfan · Super Guru

Wow - that is some piece of kit!

Not for us amateurs it seems - this is the nearest UK equivalent I could find - £565 doh

Jeff B · Veteran Member

That's awesome. Now we have the tools to generate a Teikei to Mikuni jet conversion chart.... biggrin

impulsive · Member

For the mains I've got 132 through 148, skipping 137 since that is the stock size in the US bikes.

The labeled sizing numbers are mm - as in a 132 jet is 1.32mm which is .0519". All of them pinned correctly to 3 decimal places. I didn't get nuts checking them to the 4th place.

See the bore of the upside down main jet in the above pic?

Stock main is .103" diameter and .118" deep. The ebay mains are .098" with the .099" pin partially starting. This equates to about 3mm. They are .136" deep.

How this difference will affect performance I have no idea.

Pilots are sized same way: 50 is .5mm = .0196. I've got a 50, 52 & 55. Again only checked to 3 decimal places. Using pins, 50=.019", 52=.020", 55=.021".

The hole at the screwdriver slot end measured .050" stock pilot & .051" ebay pilots. I neglected to check that depth.

From the other end(side w/the little holes), bore of the stock jet is .059" & depth is .438". The small holes along the side are .031".

Ebay 50 & 52 pinned .075" dia & .454" depth while the 55 pinned .076". Side holes are .030" and there are 2 additional holes vs stock.

Hopefully this makes sense!

ttr steve · Super Guru

Thanks for posting all the info, will defo have a sort out with stocking some, as Mr Yamaha is only now supplying me 2 sizes cry

impulsive · Member

No problem, glad I could contribute something useful.

If there are jets from other brands people are interested in, I could get them and measure for comparison.

Spyrious · Veteran Member

I ordered a VM28/486 52.5 and a N102/221 140 from ebay.

dlee22 · Senior Member

Wow, glad I posted this, heaps of shared info - thanks guys!

Jeff B · Veteran Member

So can we assume that the Teikei jet sizes are the same as Mikuni?

Jeff B · Veteran Member

For both pilot and mains?

ttboof · Super Guru

Will see if I can find out my local bike shop ordered jets for mine with out any hassle didn't check where they were from. Ended up going back to the standard main and up one size on the pilot

Will drop in and ask next time I'm going past

Spyrious · Veteran Member

I received mine.They dont look like the on the pictures of the carb rebuild.I'm not sure if i can use them...

-- Edited by Spyrious on Wednesday 22nd of January 2020 04:39:45 PM