[Onski69]

Just did an XC race yesterday. Bike made it the 80 minutes. Barely. Ran out of gas minutes after crossing the finish line. And I was not running near as hard as I did on my old 450. Do these really suck that much gas?

Specs
'87 stock bore, just redid top end, had 135psi prior to hone and new piston/ring job, single gasket head gasket, 50/50 mix av gas and 93, Lucas 36:1 oil, .022 plug gap, 158 main, 42 pilot, air screw 2 1/2 turns out, choke/throttle screwed all the way in, fmf gold pipe, foam filter with per filter lid cover. DGH needle, clip on top groove. New throttle cable.
It was almost 80 yesterday, low humidity here in texas.

Second question, I'd let it warm up for a few minutes and then have to really hog on it to clear it out or it just bogs and sputters real bad. Smokes a lot. But after a few quick third gear runs, it clears out. Racing it though after that I have no issues with it loading up. Wouldn't clear out by just revving it, I have to have a load on the motor. Really but absolutely no bottom end. Once power and kicks in its definitely a handful. Plug chop shows a good chocolate color but the plug ring is wet. Electrode and ground strap are not.

So with the needle at the top already and pilot at 42 and choke/idle screw all the way in and it still running rich down low, what else could it be?

 

[american opel]

hopefully the compression came up a lot with new piston and rings..it should be 165-185 stock..1 1/2 hours of hard riding doesn't sound too bad for a tank of gas,but we run mx so I fill up between rounds....loading up at an idle is common and atleast it's cleaning up quick.jet's actually seem alittle small but it doesn't sound too far off for stock.try gapping plug .018.that might help.what kind of plug are you running?8-9-10?with the needle all the way rich,you might want to go with a bigger pilot so you can run the needle in the middle.this way you can adjust more for temp and altitude.

 

[Onski69]

The track was 5.1 miles per lap. Did 5 laps, just under 26 miles on a full tank of gas. (2.6gal). That's 10mpg. That's real, real bad, isn't it?

 

[Onski69]

Needle clip is all the way at the top, leanest setting. Plug is a BR8ES. Altitude is pretty consistent at 750' asl.

 

[C-Leigh Racing]

Sounds like the pilot was to big & every time you backed off the throttle it was loading the bottom end. Or, either the float setting off & bumps causing the float to bounce & over fill the bowl making it over rich that way.
Reads like the main was ok, carb just putting to much fuel in at off throttle times.

Humm, 10 mpg, I dont know but it sounds good to me, cause we burn up 5 gallons of 110 mix on a Sat night race event, practice, heat & main event.
Neil

 

[btw250]

So is it normal for first startup and be loaded up with fuel. And takes a while to clean out.

 

[Onski69]

I know they'll load up after a bit of idling. I've heard of the mix not atomizing well when idling and fuel/oil pooling in the crankcase which requires it to be ran hard to clear up but I thought some good revving would do it. Not so much here. It does make me think the pilot is too fat. But it's already at a 42. Do they even make one smaller? Can't remember reading about one on any of these forums. Like a 40 or 38. Unheard of almost, isn't it? I'll try it but it just had me thinking it may be something else to cause it to run this rich. With an air leak somewhere, that'd lean out the mixture, correct?

 

[acecarlos]

Just did an XC race yesterday. Bike made it the 80 minutes. Barely. Ran out of gas minutes after crossing the finish line. And I was not running near as hard as I did on my old 450. Do these really suck that much gas?

Specs
'87 stock bore, just redid top end, had 135psi prior to hone and new piston/ring job, single gasket head gasket, 50/50 mix av gas and 93, Lucas 36:1 oil, .022 plug gap, 158 main, 42 pilot, air screw 2 1/2 turns out, choke/throttle screwed all the way in, fmf gold pipe, foam filter with per filter lid cover. DGH needle, clip on top groove. New throttle cable.
It was almost 80 yesterday, low humidity here in texas.

Second question, I'd let it warm up for a few minutes and then have to really hog on it to clear it out or it just bogs and sputters real bad. Smokes a lot. But after a few quick third gear runs, it clears out. Racing it though after that I have no issues with it loading up. Wouldn't clear out by just revving it, I have to have a load on the motor. Really but absolutely no bottom end. Once power and kicks in its definitely a handful. Plug chop shows a good chocolate color but the plug ring is wet. Electrode and ground strap are not.

So with the needle at the top already and pilot at 42 and choke/idle screw all the way in and it still running rich down low, what else could it be?

The jetting sounds low to me already. For SoCal it would be way lean at 0-1000', 80F, 35-50% Humidity. I also don't like your needle position, this tells me something else is not right. If your IGN is weak, or the engine is getting a poor spark, fuel wastage is high. FYI...and as a reference in the old Desert Races on Ported OEM cylinders running Race Fuel we would get around 2 hours on a full tank of gas going a lot further than you did.

Carlo

 

[Onski69]

I run a Moose foam with oil and my lid is full of holes drilled in it. I run a cotton cloth mashed between the lid and box as a prefilter. Saved my four strokes numerous times. It gets very dusty in most races here. I just toss them after each race. Would that combo cause my carb to pull more gas through? Requiring the smaller jets and/or suck more gas? I really don't want to open up the box anymore if I can avoid it. I know most guys try and run open lids, big less restrictive filters, etc which leads to more air and bigger jets. But my situation is kind of the opposite so wouldn't the opposite then be true? Or am I being overly cautious and just toss the lid and prefilter and just run the foam oiled filter?

 

[acecarlos]

The more restricted the airbox or filter are, the smaller your jetts will need to be. As an example, just removing your lid or outerware will lean out your engine.

Carlos

 

[Onski69]

Figured as much. Didn't want to run it too lean though. Sitting at a 42 and looking to drop to a 40 or even 38 really scared me especially when I couldn't find anyone else on here running a pilot that low. But then again I haven't seen many on here with stock motors running dual air filtration on them either. I always have to make things difficult.
Thanks for the reassurance Carlos. That may explain some of the gas-guzzling issue as well. I had the throttle open more than it should have been and it was probably just dumping fuel in. Not the correct amount either. The bottom end wasn't responding and letting the motor wind up, just bogging it more. So what do I do...give it more throttle. Like that's gonna help. Shoulda recognized it when I was racing but I was too busy getting the crap beat out of me. That's what I get for not running a stabilizer and stock shocks. lol

 

[acecarlos]

Let us know how it goes for you....

Carlos

 

[Onski69]

After some screwing around, I pulled the prefilter off, set the pilot at 40, AS at 1 1/2 out, main at 155, DGH needle on middle clip. Seems to run very well. Plug looks a bit hot but I haven't been able to really open it up either. High 3rd, low 4th is about all I was able to do this weekend. Had a 38 in it but when it started cold it revved very high like the choke was stuck on. Figured that was probably too far off. I may try the 42 again now without the prefilter but it just scares me to run without one in a 90 minute long race in this Texas dust. I'm hacking dust up for days after the race as is, I can only imagine what the motor could suck up.

 

[wifedup]

The track was 5.1 miles per lap. Did 5 laps, just under 26 miles on a full tank of gas. (2.6gal). That's 10mpg. That's real, real bad, isn't it?

Haha that sounds about right on, i can do a 24 mile loop on a trail(pretty wide open 4th and 5th riding) and have a splash left in the tank. A 4 stroke will demolish us in mileage everytime...

 

[acecarlos]

After some screwing around, I pulled the prefilter off, set the pilot at 40i AS at 1 1/2 out, main at 155, DGH needle on middle clip. Seems to run very well. Plug looks a bit hot but I haven't been able to really open it up either. High 3rd, low 4th is about all I was able to do this weekend. Had a 38 in it but when it started cold it revved very high like the choke was stuck on. Figured that was probably too far off. I may try the 42 again now without the prefilter but it just scares me to run without one in a 90 minute long race in this Texas dust. I'm hacking dust up for days after the race as is, I can only imagine what the motor could suck up.

Try a Uni filter, well oiled. The two stage filters are very restrictive, likey why your jetting Is as low as it is. Bottom line, if it works for you, then you are on the right track.

Carlos

 

[Funwith250r]

Check your reeds. It sounds like your trying to jet around a chip or a crack in the reeds.

 

[Onski69]

Check your reeds. It sounds like your trying to jet around a chip or a crack in the reeds.

When I first got the quad, I went to take the carb off and the intake manifold boot split in half. Got one off a CR and changed it out. I had the cage off then and they looked ok. I do have a Boysen RAD valve I just scored off eBay on the way so I'm waiting to jet any more until I get it in. Very excited!