Bike spontaneously won;t run while off choke.

[TeeCat]

JUST like that.

Some of you may have followed my conversion to a single Mik 36mm roundslide. The bike was running better than it ever had just afterward, late last season, almost dialed in, and then came winter. So, the bike sat with a full tank, and stabilizer.

Twice - the second time being today - I fired her up and let her come up to temp. She came off the choke and idled fine, so I took her out to the curb today and was getting ready to take her around the block, when she just shut off.

Long story short... she'll fire right up with some choke, but even while holding the throttle a little open, off the choke, she'll stall. Every time. Fires up again on the choke.

Pilot, right? That's my guess. But WHY, all of a sudden?! Good lord... the carb is barely dialed in. What do I do in this situation, with a Mik 36 (other than kicking the stupid bike over in the street in front of the neighbors)?

Thoughts?

(This is rapidly becoming no fun any more.)

TC

 

[bpd106]

It sounds like you're right on with the pilot jet. Did you use any fuel stabilzer over the winter? I do in all my stuff, lawnmowers, bikes, everything. The snowblower even gets it in the summer. Prolly just got a piece of crud that found its way in there. I worked on a little Honda XR70 last spring that had the same thing happen after sitting all winter.

Good Luck!,
bpd106

 

[littlebill31]

I would say pilot and I would really consider a good, very good, carb cleaning. The pilot circuit ports are very small. Even with stabilizer in the gas there can be a build up on the inside of the carbs. After running it, a piece of the varnish could have sluffed off and found it's way into a port. Especially if you didn't drain the float bowls before winter.The stabilizer only really works in the gas, and when you have a full tank. Air space causes fouling.
A cleaning never hurts, but only helps. Always do a Spring cleaning.

 

[TeeCat]

Guys, I did use stabilizer, and I'm inclined to agree with you about the piece of dirt or something. The carb, though, is quite literally brand new, as are the manifold and related components. So, that carb is immaculate. I plan to drop the bowl, though, pull the pilot, and inspect/clean it. But this happened all of a sudden, so I'm thinking something has found its way to somewhere it doesn't belong.

Thank you, guys... will have to do this when I have time. Always something! Wish I could just ride the thing once in a while!

TC

 

[weekendrider]

TeeCat, You could try letting it run some, maybe some fresh fuel through the system will start it flowing. The lazy way out but.....
Did you drain the carb or leave gas in it?
On the question of why so soon. Alcohol evaporates quicker than gas and you aren't dealing with the same fuel you grew up with.
Get rid of that nasty ass carb anyways, you know you want EFI. That would give something to do this summer.

 

[littlebill31]

weekendrider has a very good point. The new gas, E10, actually degrades certain rubber parts. A study was done by Harley and Cycle World and found that fuel milage was reduced and rubber parts were somewhat damaged. Because of what E10 is, it will evaporate quicker and also because of what it is made of it has a higher water content.
Ask anyone who has a boat about E10 and they will wince. It doesn't take long for gas to foul carbs.

Stabilizers do work well, but look at some of the tests independent companies did with nails. They filled several jars with the same type gas and added several different types of stabilizers, placing a 10 penny nail in the fluid. A few of them actually rusted in the fuel. Some fuels seperated from the stabilizers as well.

I bought a brand new Mercury 4-stroke engine for my boat last year. It says right on it, "Do Not Use E10". And they say to add 3 different types of Mercury stabilizers, fuel additives, ect. everytime you fill up. They aren't cheap and when you get fuel from some ass station with dirty fuel tanks you get junk in the tank. I have an aluminum tank, I got fuel, had a problem, drained the tank and found rust/gunk. Hmmmm, rust wasn't from me. It was from the shitty tank in the ground at the gas station.

 

[xjwmx]

They say if you see a tanker truck at a station, go on to the next station. Loading the ground tank from the truck whips up all the crud.

 

[TeeCat]

Thank you guys very much for the detailed responses!

I think we're all on the same sheet of music here. I considered possibly trying to run the bike for a bit up to temp, and then seeing if I can try to balance the choke and throttle to try to keep it running and cheat/muscle whatever may be in the pilot circuit out before I drop the bowl. But just so I'm clear, in a Mik round slide, when the choke is on, no fuel is passing through the pilot circuit, right? I think they're physically separate, from looking at the drawings.

As I recall, last time, I ran the bowl dry, but I could not swear to it. I also run an in-line filter habitually, and also keep a rare earth magnet right in front of each petcock (on the outside/underneath of the tank)to try to minimize movement of any metallic junk through the petcocks. But this bit of debris, if that's the issue, may be the result of fuel degradation, as you mention. But it happened so suddenly that I suspect dirt, a stray bit of varnish, etc..

Bill, do you think additives might be a good idea for our bikes? I mean, this E10 situation is just crazy!

I'll try to crack whatever the problem is loose when I get a chance, before I open the carb, and I'll keep you posted.

TC

 

[littlebill31]

This is what I use. http://www.starbrite.com/sproductdetail.cfm?ID=1537 in my $15,000.00 boat engine, all my cars, and bike. I have a water seperator on my boat, which, if there is any, catches water between the tank and the engine. You will always get a little, but I did notice a major difference when using the enzyme. I can see the fuel go thru the clear filter unit, then (due to gravity) the water falls into the bottom and the pick-up (which is higher) pulls fuel into the engine. Now, if I gun the engine to the RMP limit you can see the gas surging and bringing some water with it, just from the very high flow rate. The starbrite does a damn good job.

E10 cause condensation, end of story. If the tank is completely full there will be no way for it to expel into the tank. Half-full it will. I also live right on the water with high humidity levels and salt air. You ask 20 people what they use and you'll get 20 different answers, but I do like the starbrite. I know a bunch of captains and mechanics that swear by it and will kill the SOB who started the E10 craze. Some marinas, and this is no shit, smuggle regular gas to their docks and sell it for a premium price. They have to sell E10 on the water here. Freaking rip off and it's about $1.50 more a gallon. What else are you going to do if you need gas on the water. Got you by the balls.

Ever notice that alcohol engines are a little differently built then gas engines?

 

[TeeCat]

Bill, thank you for the link! I'll have to investigate this stuff.

It's too early and quiet around here (Sunday and all) to mess with the bike this morning, but I might have a look at it later today if I get time. I'm still hoping I can break this loose without dropping the bowl. It's just a mater of twisting the carb, dropping the bowl and pulling the pilot jet, but still...

Thanks again, Bill!

TC

 

[gggGary]

That big Ole thing is hanging out there in the breeze, what'll it take 5 minutes to the bench? R&R it bud! I have no issues with ethanol AFTER it has stripped all the old varnish off of everything in the fuel system and run it through the engine! All the bitch'n about ethanol stops after it has been in use for a year or so. Fiberglass gas tanks are a different story.

 

[TeeCat]

Gary, it looks that way, but it's actually a pain if I have to pull the carb off the bike. That throttle cable is a major pain in the ass to reinstall and adjust, so I'm trying to avoid yanking the carb. Might be able to get the bowl off without twisting the carb if I can find a little 90-degree phillips I had...

 

[gggGary]

Twer it me, I'd check the idle mixture screw, run it in counting turns, take it out, blow carb cleaner through the hole reassemble. see what happens.

 

[gggGary]

Just unscrew the cap and leave the slide and cable assembled on the bike. That's how we always used to do it.

 

[TeeCat]

The carb cleaner through the mix screw is a good idea... might have to try that.

Your second idea is how I did it when I rejetted the carb to its current state. I'll do that again if I have to pull the carb.

 

[TeeCat]

Well, I went out there to fire the bike up and see what today would bring. But this time, I had a hell of a time just getting it started, even on the choke. It would run for a few seconds, and then spit out the carb bell. Once, I managed to get it running at high idle on the choke, and it would take throttle then, but as I de-choked, it would shut off. The main difference today was that it just was so difficult to start at all. I put it on the charger afterward just to be safe.

So, I suppose the carb will have to come off, and come apart. It's literally got maybe 40 miles on it since I did the conversion, and for the last 30 or so of those, it ran better than it ever has. So, what changed?

The seasons. I have to believe that this is somehow fuel (degradation) related. Nothing else has changed. I'm running a PAMCO since last year (or the year before that?), and had set the timing... seemed to be fine when I put the bike up this fall. The valves were in spec. Got juice. But "something happened" between the last time I fired the bike, and now. Brings a new meaning to the term "ghost in the machine".

I didn't work on it any more today because I'm just not in the mood... too frustrated. I'll have to go at it with a clearer head. One thing is for sure, though: I simply can't afford to spend another riding season locked in mortal combat with this bike, for a lot of reasons, most of which have to do with plain ol' practicality. There's just a point of diminishing returns, you know? So, I have some thinking to do, but I dont want to make any decisions when I'm pissed, especially since I'm retiring next year.

One thing I did notice this afternoon, though: the air intake that I had made has an ABS plastic runner. I noticed today that it had shifted position, I suppose because my left leg had bumped it while I was kicking. So I'll have to go back to the drawing board on that. But more than that, the plastic had broken right at the place where I had two little button-head machine screws holding the soft plastic collar to the ABS runner. So I'm almost hoping I find a sliver of plastic, chrome coating, or the like in the carb whenever I feel like opening it up. The more I think about it, this might not be just coincidence.

TC

 

[TeeCat]

Oh, and assuming that I find and correct the problem when I pull the carb, I may have to address the air intake problem (sticking out too far and being bumped by my leg) by going with something like this. Not my first choice, but I think it may work, space-wise, as long as it can micro filter. Another option is this. I liked my arrangement, functionally, but it was just too bulky.

But first, I have to find the time to get her running normally again.

 

[CDNTX650]

welcome to owning an old bike....you want no problems you buy newer or efi. It probably is the gas. Thank fuck we hardly use any ethanol, and shell v-power has none at all. Both the KLR and my XS have been sitting all winter with v power and no stabilizer. both fired right away and ran great with no bad gas stink.

 

[TeeCat]

Well, I left the cable and slide assembly in place, pulled the carb, and took it apart as though I were going to re-jet it. I need to get some more carb cleaner, but I looked at the main jet, and needle jet, and the pilot jet, and didn't see anything obvious, which was a little disappointing, though having no crud in the bowl is reassuring in that the filter is doing its job. I will say, though, that the first peek at the pilot jet under light had me thinking that light might not have been getting through it lengthwise. Might. Once I blew on it, I could see down it.

I still have not actually hit the carb with cleaner, but (per Gary) should I still pull out the air metering screw and blast that passage? Also, any other passages I should know about? I'm looking at a diagram, but want to make sure I clear everything that could cause an issue. Also thinking seriously of getting rid of this tank of fuel.

Thanks again...

TC

 

[ReycleBill]

I am defiantly sold on Shell gasolines-- regular in my cars and truck, high test in my bikes. Everything I own runs better after having switched to Shell exclusively. That said, it took a few tanks to notice a difference.

But even the Shell gas won't fix what is troubling you right now.