NEED HELP!!!

Ok so here is what I have going on. My bike will run fine until I get into tight sections of the trail and the temp gets up to about 200' F. Once it is in a range of + or - 3 degrees the bike will not respond to the throttle and will pulse as if I am hitting the throttle and then letting off completely every other second. I have taken the thermostat out of the bike and am running strait engine ice coolant. I have the carb jetted to 68s pilot, 4th down on needle, and 175 main. I have an open exhaust and a K/N air filter and its also uncorked so it breathing really well. In the tight sections of trail I am usually only using the throttle in the off to 1/4 range so my thought is to increase the pilot jet to a 70 or 72 and see if that helps with overheating and pulsing. If I let the bike cool back down to below 200'F it runs like a champ and pulls really hard.

Now I have to admit that I have not adjusted the valves yet and will as soon as I am off work but do you guys have any other ideas.

I really enjoy my xr650r and want to keep it but if I can not figure out a way to ride it in tight trails I am afraid it will have to go. Any suggestions would be greatly appreciated.

My idea is that the bike is running to lean in the lower end of the throttle and is causing the pulsing and temperature rise. I hope by running a bigger pilot the extra fuel will help to cool the process.

What do you think? Any other ideas?

Edited by paulsinger, 01 August 2012 - 04:46 PM.

Where you at? I ran a 68s pilot 165 main, third on needle. At 3-9k elevation here in Idaho...Before switching to the Edel carb.

if your going that slow and the bike is overheating is it boiling over? were are you getting 200* temps? is that oil or coolant? ideal oil temp is 210-220. no idea what coolant should be at but 200 doesnt seem that hi. If it is in fact overheating a fan is what you need search the board for fan and you will get a million responses.

@ scalejockey- I am in Moscow and am riding in the 2000 to 5000 feet above sea level range.

@dubkatz- No it is not even getting close to boiling over. I have read (take with a grain of salt) that the bike will boil over at about 230 degrees F but I can not even get close to that temp. It starts doing the pulsing thing way before that, closer to 200 degrees F and becomes un-ridable.

I am getting 200 degrees at my vapor trail computer sensor which is in line right before (think above) the thermostat housing. This it the coolant temp. I do not know what the oil temp is.

I am not sure that a fan is going to be able to make that much of a difference but it is worth a try. I think I have bigger issues than a fan though.

Does the idea of the pulsing coming from a lean fuel mixture and pre ignition match up with your guys common sense gut feeling? It does mine but would like a second opinion. I know "they" say that if the mixture is lean temps will rise quickly. It just seems odd to me that I can not even get the bike to a boil over state before the pulsing starts.

Do you guys also have a feeling of what the differences I should hear/feel between a lean or rich mixture in a 4 stroke? I know I can check the plugs but they always seem to look pretty good to me, a little off white/grey and pretty clean.

Also, I am the river ranger on the main salmon river so I will be gone for the next 7 days on a patrol so if I do not respond in the next couple days its because I am on the river and not because I am not chomping at the bit to hear your responses. Thanks for your help.

Edited by paulsinger, 02 August 2012 - 05:10 AM.

I had this happen on my xr600,

it was boiling gas that did the EXACT same thing on my bike

I had no frame strap/isolator between the ims 4 gal tank and the frame with hot oil

whenever I would ride slow 1st gear singletrack I would get this stop go stop go feeling

It turns out my gas was too hot and BOILING!

so I bought a new clarke oem tank, and made a leather frame strap to prevent the heat of the oil tank to permeate the gas tank

no issues for the last 6 months

Dont know about the pulsing but fourth notch seems wrong

Way too rich for that elevation and those mods.  That's about the elevation we ride around this part of the state.
A "Ranger for the Main Salmon"???? OK,,,you went to the top of my u suk list! LOL! I want your job!

elsalvadorklr, on 02 August 2012 - 04:36 PM, said:

______

Dude that is a great idea. I wonder if the fuel in the bowl is also boiling. I will insulate the tank, I do have and oversized tank that is not insulated. I wonder if some of that metal tape for exhaust pipes would work. Where at on the tank did you insulate? Thank you so much. I will try this. As for the notches on the pin my bike just seems to run a lot of air through the engine so I need the fuel.

ok heres is the deal

I have pics showing what not good enough metal tape does to an engine, spoiler IT MELTS!

SO

use leather for the frame strap and or a combination of leather and foam like stock

second its aftermarket tanks that get hot gas, they are too close to the fins on the head(most people dont see this happen because they dont push theor bikes hard enough) not bragging its just most people with oversize tanks dont go singletracking or enduro riding...so you never really find out

its not the fuel in the bowl thats boiling its the actual gas in the tank thats too hot and doesnt combust properly entering the carb/intake

second this happened to me only in slow singeltrack very slow stuff and not enough air was moving, as soon as I would get out into the open no more problems

I was also jetted rich just like you which made it all worse

so first off JET for your altitude and go by your bikes response/feeling



I think you have a combination of hot gas/overheating and rich jetting, bit will guve you that hiccupy fat, see saw  hobby horsing you get when the riding gets tough

beleive me it was a nuissance going up some rocks and then you get this go/stop/go/stop almost wheelieng effect

funniest thing ever if youre not the rider


dont know about the xr650r but you could try making some insulators/frame straps like the xr6 has

anywhoo

good luck

POST YOUR RESULTS!

So here we go. I bought some high temp tape (good stuff that will not leak) and covered the inside of the tank. I also set the jets up to spec and also adjusted the valves. I then checked the gas cap and found out it was letting air in but would not let pressure out even if it was in the vertical orientation. So I checked the stock cap and it was working great and fit on the clarke tank so I just put it on. If you know anything about thermodynamics it the pressure increases the fluid can boil at a lower temp so I think this was a lot of what was happening.

The exhaust valves were good but the intake valves had zero play in them so I adjusted them.

I took the bike out today and let it idle in the sun. It got up to 220F and had no hoble horse feel. I think the problem is solved for now and man did the bike have a lot more power.

THANK YOU all very much for your help especially
elsalvadorklr

You were right on the money with your info, thanks.

Paul

damn dude

you made my day! jajaja

glad to hear i could help
x2 on the gas cap vent

I always always even while riding release pressure from the cap

sometimes the sun, temps and all conspire to create just too much pressure...

even though everything works ok...

bottom line is many things can create similiar situations/problems

post some ride pics when you get the chance!

take care

christian

So I lied, the bike is doing it again. I have got the bike up to the 205degree range on the coolant and it started pulsing. I quickly drained the carb and caught the gas from the float and the gas was cool. I have now put the tape on the inside of the tank, wrapped the headers. Any other ideas why my bike would be doing this. I am running 3rd clip 68s pilot 168 main at 2500ft asl and 85F day outside.

Thanks for your help!

thought you jetted down too

your still to rich no?

the 68s is THE pilot for the xr650r but at 2500f plus feet you need to at least jet down the main

I still firmly beleive that your issue and mine was a COMBINATION of fat jetting and hot gas...

jet down till you feel uncomfortably lean THEN jet to where you get back some "power" back I say power because LEAN actually performs better, acceleration, snappiness, control etc..

its a common myth that fat jets will make more power...

ps. if jetting changes nothing then you know its heat related electrical issues...thats a little harder to fix, jajaja mostly has to do wuth replacing parts and that sucks1 jajaja

Edited by elsalvadorklr, 23 August 2012 - 09:41 AM.

I do not think I need to jet down the main. According to      http://www.xr650r.us...ting/           I should be right in the range. I am at 68s, 3rd clip on the needle and at 168 main.  Why would you think that I am still to rich? When you say jet down to I feel uncomfortable what do you mean, what do you think I can expect. Even right now I am getting a lot of back firing when I let off the throttle. I am also starting to get a hanging idle. Could be that I just need to readjust the throttle cable. Also do you have any experience adjusting the carb floats? I was starting to wonder if the could be affecting something. Thanks for your help.

I've had the same problems in the past on other bikes, and it was usually an air/vacum leak somewhere that was causing it. Have you checked the carb boots (from engine to carb and carb to airbox) to see if they're cracked/split/leaking/loose? Even a tiny leak/crack can cause BIG problems that all the jetting adjustments in the world won't fix.

paulsinger, on 23 August 2012 - 10:07 PM, said:

well jet down till you feel lean means just that...till you start surging at a certain rpm then jet back up...

but befor you do any of this like old dog says you have other issues

1. you shouldnt have excess backfiring or close to none when letting off the throttle especially with your jetting
2. HANGING IDLE is a huge indication that you have an air leak

so

make sure the boots on your carb are sealed, check with some carb cleaner sprayed around the intake boot sealing area and airbox...

FLOATS

yes

I beleive the xr650r is 17 or 18mm from flat part of bow to flat part of float

on the xr600 its 15mm

in reality unless the floats are installed upside down it really is hard to bedn them out of shape

for example if you park the bike on the stand are you getting fuel spilling out the vents? thats a sign you need to readjust your float

hanging idle can also be caused by a dirty pilot jet...

fix this before you start jetting

like mentioned before its really hard to start jetting if all of your systems arent 100 percent

no point in jetting for example if your stator is acting up or you have weak spark or a muffler full of holes or an airbox with a torn boot. etc..etc...

Edited by elsalvadorklr, 24 August 2012 - 08:14 AM.

I noted that the "intake valves were at zero"? Might check them again,they might be sucking into the head.They can be good for a short while then go out again once they start moving(or cupping),, Then problems show up when the bike is hot. Had mine do this last year.
Also the float level is picky on these..

Edited by scalejockey, 24 August 2012 - 12:12 PM.

Do you use one of those one-way valves on your vent line?  If so, try just a straight vent tube.  Seen this problem several times.

Old Dog, on 23 August 2012 - 10:31 PM, said:

elsalvadorklr, on 24 August 2012 - 08:12 AM, said:

scalejockey, on 24 August 2012 - 12:11 PM, said:

Mikie1, on 24 August 2012 - 12:52 PM, said:

So after reading all your posts I went out and really tore into the carb. I adjusted the float, took out the main jet, pilot jet, air fuel screw, and the main emmusification (spelling, sorry) tube that holds the main jet. And to my surprise the little needle guide that is held in by the emmusification tube was backwards!!!! So I flipped that around. Put the jetting to 65, 3rd clip, and 168. Buttoned it up and messed with the air/fuel screw while at a low idle, set it about half way through the range. Bike is running a lot better, even at high temp, still pulses a bit, but I am going to take your guys advice and keep jetting down until I feel a difference. I also checked the plug and it was black but burnt black not like oil black so I checked the manual and it called it a carbonated plug and that the mixture was to rich so I am going to keep going down in size. The bike already responds much much better. To be very honest I think I put the needle guide in backwards the other day which obviously is causing a huge hanging idle, my bad. BUT, now that it is the right way I am still having the same problem pulsing. I am really starting to be convinced I am jetted to rich.

So I tried spraying carb cleaner around the boots on the carb and the engine no change. I will re check the valves. What do you mean by the one way valves on the vent line, I am not sure which of the 4 tubes coming of the carb is the vent line. Thanks for all your help, I think I am getting close.

Paul

JEEEEEEEEEEEEEEEEEEEEEEEET DOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOWN JAJAJAJAJA

im going to become the JET DOWN guy on here

Ill leave with this

my 88 xr600 comes jetted fat from the factory on hondas beleife that the twin pipes needed such big jets, the 88 xr600 comes witha  165 main! when other year bikes come with a 152!

I had a burnt black plug for ages and ages UNTIL i finally got the balls and said screw it, your getting a 152 jet(this is with a different header and exhaust but still)

lo and behold the plug turned a nicer brown color, still rich as I was blipping some soot every once in a while

after getting a mikuni tm38 carb as part of a fork swap deal a way back and finally trying it out

I have a perfect tan/white plug with no indictaion of either being lean(deposits) or rich with soot...its perfect!

My biggest indication of being rich was not only blipping some soot and having a dirty fender but it was your symptoms when riding slow, hot gas and also every once in a while when goosing the throttle I would get NO ACCELERATION, like I had to twist the throttle twice to accelerate

how I let that behaviour seem normal or stay for so long is beyond me

as soon as I jetted way down, I got crisp throttle response, better gas mileage and no surging or hesitation...

so thats why I say jet down till you feel uncomfortable...it takes some guts to do it,

only when doing drastic changes like that will you really see what jetting does

its hard to get really good results when only going up or down 1 size

also its always one change at a time

lastly did you check for air leaks?

christian