Ken448

Somethings going on with my motor, and Im stumped... After having a 2.5 that ran great for 6+ gallons. This OS is giving me a challenge LOL. Lets start with the strange idle problem.... I doent have anything that resembles a smooth idle, it sounds more like a 2 stroke dirt-bike.. ne-ne-ne-ne-ne and idle speed isnt steady at all (raises and lowers by a couple hundred RPM and does this over and over) If I try to lower the idle to make it sound smooth, its too low, and stalls. LSN is flush right now and never really gets too far from there. Next.. Temp issues yesterday. Driving at the track, and its putting out a beautiful smoke trail at all times, and performance is down slightly, so I temp it to see how much room I have to adjust some zip in, and its at 270!?! Checked with a Raytec gun with a tip adapted to get right on the glow plug (will explain if someones interested) and someone elses gun just to be sure. Now, normally, this motor has ran FAST and hardly ever above the 210-220 range. Heres what I have done so far:
Looked for apparent leaks around the motor (none)
Tore motor down, looked for anything out of the ordinary
found a bad O ring on the idle adjustment screw (dont think thats considered an air leak though since the screw is a mechanical setting and not a real needle)
Thuroughly cleaned carb/needles and motor before re-assembly
Piston and sleeve still have great fit (just 2 gallons through it)
Never touched the Mid Range Needle
Replaced Fuel lines (at track... no change)
Checked for blockages in exhaust... none
Replaced header gasket...
Looked at fuel tank, it APPEARS to be sealing fine, but Ill throw in a new O ring just for the heck of it.
Returned needles back to stock settings (2 turns out on HSN...that puts it about flush with HSN body and flush on LSN)
Checked all wheels/bearings for any excessive drag, everythings turning freely with no drag
Checked OWB its fine
Clutchbell bearings are new
Clutch spring is good

Im using 20% Trinity fuel, and a new Mc 59 plug
Will fire it up today and see if what I have done has helped, in the meantime, if anyone has a suggestion to something I may have overlooked, please let me know!!

redrider

Hey Ken,
I've found that the gas cap seal is the singular most important factor affecting tune and temperature. The difference between a leaking seal and one that doesn't results easily in 70* difference in temperature. I've replaced my orings with a material called Aflas (tetraflouroethylene/propylene) which is impervious to nitromethane and methanol and doesn't expand or swell. I've verified an air tight seal by submerging the tank in water and blowing on the pressure tube. Once you get the seal under control, your temps should fall back to the 220 range. My needle settings for the low and mid are essentially default settings, the HSN is 1 3/4T out most of the time.
As for the idle surging, maybe the MC59 is not quite hot enough, I always use the LC3 and never had an idling issue, I use O'Donnell's 20%.

PS. what bike is that in your avatar? I ride a VFR800 and it looks a bit similar based on what I can see of your pic.

binaryterror

Seriously sounds like an airleak of some sort to me...

Ken448

Red.. yah thats my thought on the Oring.. and is the LC3 a hotter plug than the 59?? and Yup, thats a VFR800 you got it... Waiting for the snow to leave so I can ride again!!!
Here is a better pic just after I put it back together after a low side.... OOPS!!!

redrider

As I understand it, the MC59 is rated medium/cold, the LC3 is a hot plug. I'd stick with the hot plug, it'll probably solve the erratic idle is my guess.

My bike is the same as yours, except I've got a Remus Titanium high pipe, '98 vintage. Out west, riding is mostly all year in most places. The Sierra and norcal is an incredible place to ride, check out http://www.pashnit.com/motoroads.htm
My next ride will be the Yamaha MT-01 assuming it gets imported stateside of course.

Ken448

LOL I have to ride 50 miles to get to some decent twisties and they still suck.... You prolly go to the corner, turn left, and scrape pegs! MI sucks for riding unless youre into freeway stunts LOL.. But I have managed to put 25K miles on it searching for fun! Thats high for any MI bike.

Anyhoo, Ill try the plug, and I just pressure tested the tank, it held pressure for like 5 mins. Im HOPING whatever the prob was, it will go away, if not, Ill change the whole tank (have an extra off that E auction place) But since the weather sux here I wont know til tomoow or Friday at the latest when I get back to the track.

redrider

Not quite around the corner...in San Jose we have some nice hills/mountains surrounding the Silicon Valley which is fun. Getting to the Sierra or say Wine Country to the North is a bit of a jaunt but well worth the trip.
Good luck with the temp issue.

fhm101

If you have not replaced the O ring around your idle screw, pull it out put a dab of grease around the land and run it back in to see if it helps. Any defective O ring is a potential air leak, that's why it's O ringed. Also, once you get your overall temp under control, run a few hot laps to bring it up good then bring it in and shoot it. Let it idle for a 10 count and shoot it again. If your temp drops more than 6~8 degrees your LSN is too rich, less than 6~8 it's too lean.

Ken448

Well, after replacing the Oring on the Idle screw, putting the motor back together, pressure testing the tank, putting in a LC3 plug, no change in temp or idle condition.. Im stumped, and ready to throw Mr. Revo through a wall LOL (other issues going on......... IT HANDLES LIKE CRAP! but I think the root of that finally came to light today with a completley blown front diff Im HOPING thats it for that little problem) Now the engine.... Someone have any ideas? I sent OS an Email will see what they say on Monday..

ncrego

My Feedback: (40)

I had a similar problem on a Wasp in my old Savage. After replacing every O ring and fuel tube, I finally pressure tested the engine. Turned out the front bearing was leaking. Replaced that, and it ran perfectly. MIght be worth checking. I check it by plugging the exhaust port and the intake on the carb, and attaching a piece of fuel tubing to the carb, submerge the engine in water, and blow on the tubing, where you see bubbles, you have a leak. After you do that, spray it down with Denatured alcohol to disperse all the water, and fix the leak.

tommythecat

My Feedback: (2)

That is the best leak check method i've heard so far. Cheers

tirider

You may have a tuning problem. I'm no expert but I have been reading some interesting posts on another forum. The poster (named Rolex) has some common sense information centering around the LSN adjustment. I applied the information to my 2.5R and it helped tremendously. I don't know if it's cool to post a link to another forum here but I don't want to copy and paste all the info.

http://www.rcnitrotalk.com/forum/showthread.php?t=27616

http://www.rcnitrotalk.com/forum/showthread.php?t=27897

One of these two threads may be helpful to you.

I will let the sensors decide if they want it on here or not.

Ken448

problem has been solved... it was a bad seal on the exhaust gasket (ripped stock gasket, then replaced.. 3X)Turns out there was a burr in the header shreading the gaskets.