FCR 39 jetting?

I know there is a million topics about this but here is my own questions. I have 05 DRZ SM about 18k miles. Got it last fall and rode it 2 or 3 times and it ran alright. I pulled it out from storage and it only seems to run good on full choke. I replaced plug with new NGK and has a mix of 1/4 old gas and 3/4 of new gas. Ran a little better and would idle good every now and then. It also developed some sputtering at around 35-40 mph cruising , along with a lot of back firing once you let off throttle. I pulled carb tonight and cleaned it out, and am getting 100% fresh gas tomorrow. I also plan on checking valve clearance and timing chain condition.

I have mods of

3x3

K&N filter

Yoshimura off road full exhaust

Jetting:

160 main

80 pilot air

45 pilot

2 turns on fuel screw

Around 800 ft above sea level

Does this jetting seems correct for my set up or should i change it up before I re-install carb?

Which Fcr..?? MX or slant body?? What needle and clip setting?

Your symptoms are classic clogged pilot circuit ..Check other jets while it's apart.....replace the pilot jet and clean carb thoroughly

It is the MX version, clip setting 3. Where is the best place to order new jets and gaskets?

edit has OCEMN needle

Edited by savageman2990

I wouldn't spend money on a whole new jet kit since you know the specific jets you need. Call your local motorcycle shop, 2 shops in my area have all sorts of keihien jets in stock for 4 bucks each.

200 main air jet

Remove pilot air jet

Do the o ring mod with wire

Good idea to check the valve clearances , depending on previous use and maintenance history the top end may be getting a bit tired with 18K miles.....

A little update, went to my local cycle shop today and picked up a new pilot jet and they only had a 162 main jet so I settled for that. Cleaned everything up and reinstalled the carb on my bike and took it for a drive. Its amazing how much smoother and quicker the throttle responds now and almost zero popping and backfiring it does after you let off the throttle.

I ended up with:

162 main jet

200 main air

the new 45 pilot

80 starter jet

OCEMN needle on clip #3

2 1/4 turn of air/fuel screw

at 800ft above sea level

It runs amazing, thanks for your help! This is a very helpful community! Now to tackle checking valve clearances and timing chain wear and I'm ready to go for the season!!!

Edited by savageman2990

192 main ?

I had a 185 in my FCR 41 feeding my stroker motor

A 192.. :shocked: ...&%$#@!.. :eek: ..it must be a typo as a 192 Keihin main jet is not available, I am thinking he means to say 162 or 152...

Opps, I did mean a 162! Them dang 9's and 6's always get me mixed up! :blush:

:thumbsup:

So, I've rode it yesterday and today and still have some bogg/hesitation at steady speeds at rpm around 3,500 to 4,500rpm I'd guess with out a tach, or around 40-45mph in 4th gear. Otherwise my top/low end is strong with out any stumbles or hesitation.

I adjusted the air/fuel needle to 2 turns out and it seemed to help very little. I have yet to check timing or valve clearance (plan on doing this weekend). But I also noticed two things. One I seem to have an exhaust leak where the manifold meets the head, I noticed a bit of carbon around that area. Also my dipstick threads are damaged and it doesn't seal perfect. I've checked over the vacuum line for the petcock is connected and in good condition, none of the vent lines are pinched from the carb but one of them tore and is about 3 inches long now.

Exhaust leak, somewhat hard to see in this picture

dscn0461j.jpg

Vent line that is short on carb

imag03591366852397825.jpg

So, I've rode it yesterday and today and still have some bogg/hesitation at steady speeds at rpm around 3,500 to 4,500rpm I'd guess with out a tach, or around 40-45mph in 4th gear. Otherwise my top/low end is strong with out any stumbles or hesitation.

I adjusted the air/fuel needle to 2 turns out and it seemed to help very little. I have yet to check timing or valve clearance (plan on doing this weekend). But I also noticed two things. One I seem to have an exhaust leak where the manifold meets the head, I noticed a bit of carbon around that area. Also my dipstick threads are damaged and it doesn't seal perfect. I've checked over the vacuum line for the petcock is connected and in good condition, none of the vent lines are pinched from the carb but one of them tore and is about 3 inches long now.

Exhaust leak, somewhat hard to see in this picture

dscn0461j.jpg

Vent line that is short on carb

wheres your hose clamp?

Looks like the exhaust gasket that fits the header pipe into the head is missing. It's a thick silver gasket that slips onto the header.

Looks like the exhaust gasket that fits the header pipe into the head is missing. It's a thick silver gasket that slips onto the header.

this is old. hopefully it has been found already...

Yes it has been replaced. And after a full rebuild of the carb it is running good!!!

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