what jetting are you guys that ride dumont using?

[bennieben]

1 have a 2004 with a procircuit pipe and no other mods. the last time i went to dumont it overheated on me after my fifth run up banshee hill. i was using 91 octane fuel, mixed 32-1 maxima oil, 168 main jet. i think the altitude at dumont is 900'....when it cooled down i rode it back to camp just fine. should i just use 112 octane next time instead or should i run the 91 0ctane and bump the main to 178 or less? what setup are you guys using at dumont with the same setup i have? what is your suggestion?

[bennieben]

anybody?

[DoldGuy]

BennieBen,
I would have over heated on the First trip up if I had to carry your "Big Bahooky" up that hill. I have not been out there but since nobody else has posted I will try to help. It sounds as you are about right on your jetting for normal riding conditions, but, running under a big load for an extended amount of time as you are, I would go up 1 size on your main and have a 2nd step up with me. I would also have a gallon of 110 as my last option to try. Out of curiosity why aren't you running at least 93 pump gas? Available on your coast? Hope some of this helps!

DoldGuy

[blueoval]

I've never seen 93 pump gas in California.  I havn't seen it in and around the Las Vegas area, either.  Does anyone know if it's available in these parts of the USA?   

[Friar-Tuck]

 Bennie,
  Like DGold Guy mentioned it surely wouldn't hurt  (no pun intended) to run a bit fat on the main.
   There are several other factors to consider when trying to keep the bike cool in that enviornment.
  The type of coolant you are running, and the condition of it.  The ambient air temp, and was the bike running warm prior to the last trip.
     When you line up is the bike idling for an extended period of time between runs?
 I realize the question of lining up and "hot lapping" might not be fair, it depends on how crowded the dunes are.
    But really, if you were able to make four or five runs up the hill with no cooling down between drags, that is quite a lot of work.
    Were any of the guys you were riding with have an over heating problem or was it just your bike?
  There may be a several things to take in to account.  Have you had the bike out after that trip?   ,

[bennieben]

you know what, i think you guys are right. there is not much cooling storming up a long steep sand hill and then just coasting down, and then doing it again and again. i think that i will go one step bigger than the stock main jet and use the 110 from now on too. what do you guys think, maybe a 170?

[Hillclimb#42]

170 with 110 both sound like a good plan. But I'm not riding Cali Dunes. 32:1 is a little overkill, if you're using good oil. Ripping like you are, 50:1 is reasonable, and would make the bike run cooler, if kxriders has taught me right. Excess two stroke oil will cause heat and maybe carbon. That would also richen the mixture (fuel to air),  since there would be more fuel in the same amount of charge. I also run straight anti-freeze. how did you notice it was overheating? Leaking or boiling?

[bennieben]

i was about to shoot the hill again and my buddy lined up next to me and then started pointing at the bottom of my bike. the tube that runs to the radiator cap was shooting water out of it.

[USMC 500]

I've never seen 93 pump gas in California.  I havn't seen it in and around the Las Vegas area, either.  Does anyone know if it's available in these parts of the USA?   

There is a 76 gas station here in pasadena california by my house that sells 100 octane out the pump.

[bennieben]

in las vegas, any rebel gas station has 100 octane you pump yourself. they are everywhere. just as common as any other gas station here. its pretty cool 

[Motorrad]

you know what, i think you guys are right. there is not much cooling storming up a long steep sand hill and then just coasting down, and then doing it again and again. i think that i will go one step bigger than the stock main jet and use the 110 from now on too. what do you guys think, maybe a 170?

I've seen several bikes stick due to "coasting" down the hill improperly.   
(letting motor slow you down).  If you were doing this. It could be the reason for all that heat.    Little lubrication (throttle shut off). (lots of rpm from motor braking)

[Friar-Tuck]

Motorrad makes another good point,
  engine braking on a two stroke for extended periods of time is not the same as engine braking 4 stroke.
     I remember reading that it was not all that uncommon to hold the kill button in every now and again for guys running desert/dry lakes, does that sound feasable for rolling back down the dunes to the line up area?
  Is there any other suggestions from guys who regularly run the Sand Dunes?
  Tuck\o/

[Hillclimb#42]

Its just a matter of pulling the clutch in and giving it gas a few times. "Ying Ying". A long engine braking session on a two stroke is leaning it out with the rpm's high. I use minimal engine braking. I ride a sand park here and for the most part, you don't need brakes to go down a hill, or engine braking. Any aggressive braking ,on sand, leads to front tire washing and then a tank slapper.
  Too freakin' cold here to ride anything without a heater. In the teens today. You California guys got it made. I probably have til March before slinging any roost.

[bennieben]

i coasted down the hill in fourth sometimes fifth gear. i dont use the engine for braking. my coasting down is pretty fast. i think its just an issue of the jetting being too lean, and my poor bike lugging around a rhinocerous such as i. haha.

[USMC 500]

stupid question but here goes........did you make sure that you topped off your coolant AND purged out all the air........air bubbles in certain areas of the system could cause this problem couldn't it?