where to go from here. jetting q.

[stainlesscycle]

i'm running a doma from a 300 which did not fit 100% - but it was an easy mod (cut 30mm or so off the stinger end..) i'm not sure if this is an issue from having a later subframe on an earlier bike...and the lower frame mount for the doma does not even come close to fitting. but the pipe works signitficantly better than the early gnarly i had. i haven't tried putting the messico on it yet.

[iancp5]

Originally Posted by stainlesscycle

i'm running a doma from a 300 which did not fit 100% - but it was an easy mod (cut 30mm or so off the stinger end..) i'm not sure if this is an issue from having a later subframe on an earlier bike...and the lower frame mount for the doma does not even come close to fitting. but the pipe works signitficantly better than the early gnarly i had. i haven't tried putting the messico on it yet.

The pipes for 250/300 used to be the same part number but different for the 200. I don't know if that was because of a different fitting dimension or only because the pipe was differently tuned.

[Jim Cook]

Originally Posted by iancp5

The pipes for 250/300 used to be the same part number but different for the 200. I don't know if that was because of a different fitting dimension or only because the pipe was differently tuned.

I'll share a bit of information regarding the '97-2002 FMF Gnarly pipes, which had a different pipe and number for the 200 vs the 250/300.

In 1999 when GasGas North America was the US distributor, Don Knight was desperately trying to lower the cost of the bikes. The Messico pipes were very very expensive; so one of the first things he did to lower costs was to talk to Don Emler at FMF, to get them to make a Gnarly pipe for us. (He called him Donny Emler in our conversation, so I figured they knew each other pretty well.)

GGNA sent three crated bikes to FMF to use for getting the fit correct; a 200, a 250, & a 300. (With the OEM Messico,, all three bikes took the same pipe.) Soon, GGNA was sending us new bikes with a Gnarly pipe in the crate, instead of the Messico.
With our first shipment of these bikes, during set-up, I immediately observed that the lower pipe mount was positioned incorrectly on the 200cc Gnarly pipe, and the 250/300 pipes were much closer to correct.
Other than that, the pipes were identical.

We (GGNA, and then SMS) found that the EC200 that was sent to FMF had the lower pipe mount welded to the frame incorrectly (placement wise), resulting in the different FMF pipe for the EC/XC200.

When the FMF pipes were reconfigured to accommodate the change in the engine/frame relationship in 2003 (and the Fatty pipes were added to the offerings), this was fairly well rectified; and the 200 pipe was also reconfigured a bit to be more efficient and compatible with the 200 engine. The 2003 and later (at least through the 2006, which was the last year I was a franchised dealer) 200cc FMF pipes have a different confirmation than the 250/300 pipes.

Good Riding!
Jim

[iancp5]

Back to the jetting.
I have now fitted an EEL needle on #3 with 35 pilot and it still seems rich low down but probably ok for my riding which needs smooth torque! Was going to use the thumper for the next event but may use the 200 just to see how it goes.

There's something weird going on with this 200 and one day I'll get to the bottom of it. I'm still waiting for my #7 slide to arrive. I did notice the current slide (#5) seems to have some of the surface coating being rubbed off so I'm wondering if this is the cause of the behaviour. What I don't understand is why it gets richer unless the needle seat is being eaten up. Maybe I just need a new carb?

What effect do tired reeds have?

[iancp5]

This is getting very weird.

It ran great on the EEL, idled great at the beginning, very slightly too snappy but nothing worth worrying about. By the end of a 3 hour H&H I again had the throttle stop screwed all the way in to get an idle and stop it stalling. Bizzare! Now I'm going to go exactly opposite and try a much bigger pilot and see what happens but I don't understand why it starts off idling fine then after some hard use refuses until I pull the carb apart and change something then it idles!!!!! For a while

[dank]

have you talked to anybody like ron at r-b designs, or jd jetting, and get their opinion? they may be able to think of something that we are not.

[stainlesscycle]

Originally Posted by iancp5

This is getting very weird.

It ran great on the EEL, idled great at the beginning, very slightly too snappy but nothing worth worrying about. By the end of a 3 hour H&H I again had the throttle stop screwed all the way in to get an idle and stop it stalling. Bizzare! Now I'm going to go exactly opposite and try a much bigger pilot and see what happens but I don't understand why it starts off idling fine then after some hard use refuses until I pull the carb apart and change something then it idles!!!!! For a while

change your float needle/check your float level. perhaps fuel is slipping by..hence rich running...

[iancp5]

It's not that it's rich that confuses me it's that it seems to get richer on its own!
Think I'll take the carb off at the weekend and have a good inspection. Hopefully I'll get time.

[iancp5]

Well some of the mystery is revealed. I now know why my jetting is so radically different to others running a 36mm carb. I have a 35mm by the way and I seem to have a different design of PWK! I seem to have a special recess in the slide which fits into a protruding specially shaped tang in the carb when the slide is fully closed. As I couldn't seem to get it lean enough from idle to 1/4 throttle I bought a #7 slide to try instead of the #5 and the design is quite different. With the #7 in it just revved its tits off as soon as I started it because I find the new slide doesn't have the recess and can't close completely.

Does anybody know about the carb I seem to have? Has the "tang" been fitted to better locate the slide to reduce wear from vibration?

Inspecting the #5 slide I notice in addition to the recess it has a small slot cut in it ostensibly to allow a bleed airflow?

So I'm back to my 35P, EEL needle on #2, airscrew at 3 turns and it is still too rich at idle. I am sure it is not pulling over because I tried a 42P and it was sick as a dog being so rich. I was considering dropping the needle again but am hesitant because from 1/4 ish upwards it is on the edge of lean until the main takes over. It's just idle to 1/8 that it's rich. Can I get smaller than a 35P I wonder?

[dank]

so is it still a keihin pwk model? they list the pwk35, and the pwk air striker.