650 Turbo cutting out.

OOPS, posted in the wrong spot, so I reposted here.

I have an odd one, or maybe not.

I went for a long ride today, and at about 20 miles the boost guage starts getting erratic, and the engine begins to miss. It is almost like it is running out of gas, but the boost guage doesn't make sense.

It get's so bad that I can't maintain speed and have to pull over. It then dies altogether, and wont immediately restart.

I play with it, turn on the primer and flood the carbs. Then hold the throttle wide open and get it started. It is now running nearly perfectly, with just a very slight miss. Prime off, petcock in run position.

I decide to turn around and go home. The bike runs great, boost guage and boost working fine, everything is fine.

However, at about 20 miles it does the exact same thing again, just like before at 20 miles.

The bike turns over, but wont restart.

I then hit the prime again, crank the engine for 3-4 seconds, turn off the prime, wait 10 seconds and it starts right up again, and runs fine the 2 miles home.

It is very odd. The boost comes on as low as 4K rpm, normal is 5K rpm. The boost guage is bouncing all over, and the bike begins to miss. Just a little miss (or starve for fuel), at first, then it gets progressively worse for about a mile, then basically dies.

I suspect a build-up of crud in the wastegate is causing the turbo to add boost prematurely, and it is starving the bike for fuel. But I am wondering if any turbo owners have had a similar issue?

Jim 8)

By the way, this evening it started up and ran fine for the 5 minutes it took to put it in the garage.

 

Jim,
read boostedsupra's post sounds as though you might be developing the same problem
ferret

 

hey jim, i just now, today, bout 2 hours ago got my second turbo going, went for a ride and it sounds like we may have the same problem, or close to it, mine runs great, but at a high rpm under boost, it starts to pop and back fire from what sound like the carbs, im looking around on here now to see what it may be.i tried running the petcock in the up and down position, no change, your case may be what was wrong with my second turbo, my little check valve between the carbs was sticking, i took it off with out removing the carbs and cleaned it with some sea foam deep creep, and it fires up as soon as i hit the start button, hardly any cranking, my first turbo i had about 12 years ago did just what yours is doing, and if yours has the "power upgrade" located on the right hand side if your sitting on the bike, that was leaking vacuum, and did the same thing yours is doing, that bike even the slightest leak will mess the carbs up. i am constantly posting my progress and will keep you updated if i hear anything or figure it out.

 

Thanks, I will take a look at that tomorrow! It just might be part of the problem. It sure feels like a vacuum problem.

Jim 8)

 

hey jim, did you ever figure out what was causing your stalling problem? mine just did the same thing yesterday! i was on my way to a friends house and it started missing, so i feathered the throttle a little and seemed to keep it running.it used to pop and spit thropught the carbs, now i can floor it and it just kinda lags, doesnt really boost good at all, mine never dies but i did not give it a chance.when i got home, i let it idle, man, it felt like it was WAY HOT, so i let it idle to cool it down some, and as i was doing so, i heard a miss that was not there before. is yours doing the same? i wonder if these things have to be timed? or theignition modual may be bad? anyone have some insight on this?

 

If it's a fuel starvation problem, it is likely that the tank isn't venting, the fuel pressure regulator is stuck, or the fuel check valve isn't opening. You can try removing the cork gasket inside the cap (remove the screws on the inside of the cap and take out the thin cork gasket), you can pull the fuel check valve and make sure it is free to move (min 3 psi opening pressure), and you can try squirting some silicone lube into the fuel pressure regulator and applying some "extra" pressure, such as a bicycle pump can produce with one stroke. I did all this, plus clean the inlet fuel line to the fuel pump. There is a small conical filter there that you can pull out and clean. I took quite a bit of crud out of mine. My bike runs well now, but still needs the requisite 7 seconds or so of cranking. I also has a miss, but it is getting better. I ran some Seafoam through it as well.

Of course, your fuel pressure regulator may also be pooched, but lets hope for the best. Your carbs might also simply be full of sludge.

Also, an air cooled engine will not cool itself by idling, so if it's hot, shut it off.

If you can do it safely (clear road, a couple of empty lanes around you etc.), look back at the tip of your exhaust while it is sputtering. I saw flames popping out of my exhaust, a sure sign of fuel starvation, since the mixture is too lean to fire consistently inside the chamber, but lights off inside the hot exhaust system.

 

Bingo, that is my bike!

Unfortunately I have been at one rally or another for three weeks now, and have not even cranked the bike. I plan on working on it on Sunday, hopefully!

Riding season can be rough when you have a part time riding related business.

Jim

PS Thanks for the advice. It definitely gives me some options.

 

hmmm, after checking some one already vented my cap, and when i took off my carbs, i did mess with the regulater a lil bit, but that conical filter, i did not know exsisted. so, i think i will clean that, and mess with the regulater a bit more and give another update, other than that the bike runs good around town, lol.

 

I had similar problems like that. After looking at ALL the usual suspects how pissed was i to find a small 1-2 mm crack in the line going to the fuel pressure regulator. $1.00 piece of line and wala fixed.