Black Streaks On Piston Skirts

[grhonk]

Good call. There are other problems that will need attention after the engine work is done. This hard starting issue took place after a visit to the dealership where they worked on the carburetors. Originally I brought the ski in because of bogging problems. Dealership says it's probably the carburetors and old fuel lines. $600 later after reworked carburetors and new fuel lines, this ski has starting problems. Funny thing is, the more money I put into it, the more I feel like it is mine! Go figure. I should just buy a newer model and sell this one for parts. LOL

Other known issues: trim does not work; beeper when first engaging cap to post no longer beeps; dials do not function any more.

 

[grhonk]

I am going to rebuild it myself. I want to use it as a learning tool. It is much better to do it yourself and fail, than to have not gained the experience and continue to wonder what makes that thing tick.

I will go get some angled feeler gauges and check the RV clearance. I just got my flywheel puller and will split the block this weekend. I took out <1 once of black 30wt yesterday, but there was not water in the oil. The stator is spotless. Is it possible the dealership screwed up the carbs when they cleaned them? I wish there were one honest dealership in this world. I don't know if I should take their advice and purchase a new RV. It really floored me when I took the cover off and the RV was free floating w/o any attaching bolts and washers. I thought the dealer screwed me by not attaching the center bolt.

 

[Sportster-2001-951C-Stock]

I am going to rebuild it myself. I want to use it as a learning tool. It is much better to do it yourself and fail, than to have not gained the experience and continue to wonder what makes that thing tick.

I will go get some angled feeler gauges and check the RV clearance. I just got my flywheel puller and will split the block this weekend. I took out <1 once of black 30wt yesterday, but there was not water in the oil. The stator is spotless. Is it possible the dealership screwed up the carbs when they cleaned them? I wish there were one honest dealership in this world. I don't know if I should take their advice and purchase a new RV. It really floored me when I took the cover off and the RV was free floating w/o any attaching bolts and washers. I thought the dealer screwed me by not attaching the center bolt.

Yeah, I would just bend whatever angle is necessary in one of my existing gap gauges it it's long enough, I've got about 5 mangled sets lying around in my toolbox.

The shop manual does instruct to change the shaft oil if the engine ingests water, but I think it's tough to accomplish while the engine is mounted in the ski, and the older engines had no access plugs as well, apparently.

Of course I question if the carb rebuild was done properly, which is why I wanted to know the RV clearance. If the rebuilder installed the wrong metering spring, the carb could've been the issue. The other phenomenon that occurs is a worn RV with excessive gap, so it's impossible to narrow it down without some info on at least one or the other, preferably both if/when possible.

If I were rebuilding the carb(s), I'd use the correct metering spring and check the pop-off to confirm it's within spec prior to remounting the carb(s), it's hard to know what they saw or didn't see without physically confirming the details.

I dunno if you have the shop manual, but I think everyone should have it b/c there are important service procedures, details and specs in there and that's the purpose for reference materials. There's no way I can remember all of the details and it's silly to think anyone else does so I refer to these documents often.

Here's the deal explaining the counterbalance oil change:
http://www.seadoosource.com/reservoircheck.html

 

[grhonk]

I'm still on the fence whether I want to buy a rebuilt engine from SBT or buy a rebuilt crank to throw at it or have a local shop work on it from here. Two shops have said it will need a new crank. Some of the bearings are a bit noisy. One shop wants $100 for the bore and $225 to do the top end. I think a rebuilt crank is close to $350. It's hard to believe this is so beat up with only 100 hours on it.

 

[Crofoot50]

I'm still on the fence whether I want to buy a rebuilt engine from SBT or buy a rebuilt crank to throw at it or have a local shop work on it from here. Two shops have said it will need a new crank. Some of the bearings are a bit noisy. One shop wants $100 for the bore and $225 to do the top end. I think a rebuilt crank is close to $350. It's hard to believe this is so beat up with only 100 hours on it.

It is great to see you torn it down and are learning what makes it tick but imo noisey crank bearings just ship it out and get a Reman from SBT. You get the Warranty that helps you sleep at nite. You rebuild it andyour on your own if something goes south. Good Luck in your project.

 

[Sportster-2001-951C-Stock]

Yeah, if there's any rust pits in those bearings from water sitting there then they will probably fail pretty quickly.

Who knows for sure until you try it, but based on historical accounts the best option is having the crank remanufactured.

I think I'd go with full bore or SES though, as opposed to SBT. SBT "cheats" by taking short cuts and core value is diminished on their rebuilds when nobody else will touch them.

 

[grhonk]

Considering that those are very reliable skis(when in good condition), and it appears you're facing a decision of whether to rebuild what you have or obtain a remanufactured engine, then if it were me, I would opt for the latter at this point.

You might have been able to overcome a rotary valve issue by obtaining a machined cover to restore clearance and thus reduce the intake cross talk between cylinders but my guess is you probably have corrosion in the lower end likely to cause a rather quick failure once the reciprocating assembly begins rotating.

There can be other reasons for hard starting besides just a worn RV valve, such as a miscalibrated carburetor or less likely, some kind of an ignition problem.

Might take a close look at the condition of the jet pump and see if it's going to need a great deal of work as well, and consider the overall condition of the ski.

Well, I got me some angled feelers and the timing cover measures 0.31 mm, which is in spec. One thing I remember when I first took out the engine is there is a hose that the dealership forgot to attach to the block when they first cleaned the carburetors. I was reading the section on carburetors in the manual and they refer to this hose as a "pulse line". I have a sneaking suspicion that this is the cause of my hard starting problem and not the scratched up timing plate or the black streaks on the piston skirts. That's why when I add fuel to the air cleaner it wants to take off. This adds enough fuel to make a good starting mixture or condition (minus the oil of course).

I have a new issue now. The ski has been baking in the sun for a week and has boiled the gas out of the tank and filled my hull with gasoline! I took care of the hull with some good ol' Super Clean, but now the paint on the carburetors that were immersed in gas have delaminated. The carburetors were sitting on the bottom of the hull. The paint looks like shriveled up old skin and it peels off easily. Does anyone know how to paint carburetors and with what type of paint??? What's the process, brushed, sprayed?

 

[AdamXP800]

Wait.... What do you mean boiled the gas out?? You have fuel in the hull of the ski now????

 

[Sportster-2001-951C-Stock]

If your fuel pump pulse hose was disconnected from the crankcase nipple, the fuel pump wouldn't have pumped fuel. It it was leaking, you would've had an air leak into the crankcase which could cause a lean condition and a possible runaway at idle on the trailer.

A leak (not totally disconnected) in the pulse line would also cause the fuel pump to pump less fuel than it would otherwise.

You should be able to repaint your carbs with engine spray paint, just mask off/plug all areas where paint shouldn't enter. Paint on the throttle springs and shafts might cause them to stick, so be sparing around those areas.

Check the fuel chamber diaphragm metering spring color to confirm spring weight, or better, the pressure needed to make the metering needle/seat pop-off. If higher than spec that could cause hard-starting issues. If pop-off is too low(metering spring tension is too little), and the bottom throttle range will be too rich and flooding problems might result. Four metering lever springs are available: Black spring is 80gram, gold spring is 110gram, there are two silver springs, 65gram and 95gram, the 95gram is wound in reverse of the other three. Your carb probably should have the 95gram spring in it if your carb has the accelerator pump on it, otherwise the 80gram spring is probably the factory spec for the desired pop-off. Confirm the spring your ski is supposed to have and go with that one, measure the pop-off to confirm all is well before buttoning up the carbs, inlet seat diameter also impacts pop-off, so make sure that one's the correct size as well.

Most carb kits come with new metering seat o-rings, so replace them. I always replace the needle/seat set unless they've been changed recently of if the needle is groved or torn/damaged in some way. The rubber needle tips are impregnated with a lubricant to help them operate consistently, and the lubricant tends to wear off over time.

Pop-off is measured while the metering diaphragm is removed, and the metering needle needs to be wet with something to lubricate it (otherwise pop-off measurement may be inconsistent), such as WD-40 or other light oil.

 

[grhonk]

Ok.

All I know is the hose was never reattached and all summer long in 2012 the thing just would not start very easy. That's why I brought it in this spring to see if they routed the new fuel lines properly. I don't know why I didn't ask them to recheck the carbs. I have not driven it this year at all.

The manual does mention a little about the pop-off, but I don't think it explains it quite like you can. Is there any prep necessary for the paint to adhere to the carbs? Primer? Engine spray paint is probably at AutoZone. Suppose I could just read the label, eh?!

 

[grhonk]

Wait.... What do you mean boiled the gas out?? You have fuel in the hull of the ski now????

Yes. I had to siphon out a couple gallons of gasoline from inside the hull. Not literally boil, but I can only assume the heat in the tank expanded the gas or pressurized the tank enough to create a siphon in the fuel line to the carbs and a steady drip or flow occurred all week long unbeknownst to me. I bought Super Clear on Friday and came home to start cleaning the hull, opened the hood and what a surprise! At least there were no leak in the hull. I don't what damage it has done to the hull. The tank is almost empty.

 

[Sportster-2001-951C-Stock]

Yeah, on spray painting the carbs, I guess the right way would be to use an aluminum primer but even the factory didn't bother. I'd just degrease them before painting, a dunk in acetone once they're fully disassembled (acetone solvent is gonna destroy any rubber parts and dissolve any gummy deposits, won't attack the aluminum so soak away but watch any plastic parts carefully) will do a great job of stripping the grease off.

I would probably just get a quart of acetone from the H/W store and put it in a spray bottle, then hose 'em down. Blow off with compressed air, rinse and repeat as necessary. The paint should stick reasonably well to an oil-free surface.

I bet you could find a shop to anodize them red or blue, for the right price but once they're sitting underneath an airbox, who's gonna know?

 

[grhonk]

If these carbs are aluminum, is it necessary to paint them at all? Also, should the adjustments be made before painting so the adjustments stay in place with the dried paint?

 

[Sportster-2001-951C-Stock]

I doubt I'd paint them, I usually hose my engine down with CRC protective oil as the last step in winterization, hosing the outside of the carbs down well and they shouldn't corrode on the exterior unless maybe you ride on the salty side of the lake and the greasy grime gets washed off somehow?

Paint them if you want them to look nice, Mikuni paints them following assembly.

 

[grhonk]

If your fuel pump pulse hose was disconnected from the crankcase nipple, the fuel pump wouldn't have pumped fuel. It it was leaking, you would've had an air leak into the crankcase which could cause a lean condition and a possible runaway at idle on the trailer.

A leak (not totally disconnected) in the pulse line would also cause the fuel pump to pump less fuel than it would otherwise.

You should be able to repaint your carbs with engine spray paint, just mask off/plug all areas where paint shouldn't enter. Paint on the throttle springs and shafts might cause them to stick, so be sparing around those areas.

Check the fuel chamber diaphragm metering spring color to confirm spring weight, or better, the pressure needed to make the metering needle/seat pop-off. If higher than spec that could cause hard-starting issues. If pop-off is too low(metering spring tension is too little), and the bottom throttle range will be too rich and flooding problems might result. Four metering lever springs are available: Black spring is 80gram, gold spring is 110gram, there are two silver springs, 65gram and 95gram, the 95gram is wound in reverse of the other three. Your carb probably should have the 95gram spring in it if your carb has the accelerator pump on it, otherwise the 80gram spring is probably the factory spec for the desired pop-off. Confirm the spring your ski is supposed to have and go with that one, measure the pop-off to confirm all is well before buttoning up the carbs, inlet seat diameter also impacts pop-off, so make sure that one's the correct size as well.

Most carb kits come with new metering seat o-rings, so replace them. I always replace the needle/seat set unless they've been changed recently of if the needle is groved or torn/damaged in some way. The rubber needle tips are impregnated with a lubricant to help them operate consistently, and the lubricant tends to wear off over time.

Pop-off is measured while the metering diaphragm is removed, and the metering needle needs to be wet with something to lubricate it (otherwise pop-off measurement may be inconsistent), such as WD-40 or other light oil.

Someone told me today that a lean running engine can cause the pistons to get scuffed up. Have you heard anything like that?

 

[Sportster-2001-951C-Stock]

Someone told me today that a lean running engine can cause the pistons to get scuffed up. Have you heard anything like that?

Yes, it's quite true that 2 stroke engines don't live long lives when run too lean, this is one of my pet peeves. There are a number of ways to cause the important oil film on the cylinder walls to fail, water contamination being just one of them.

So let's consider the case of a 2 stroke that isn't exposed to the additional hazard of water ingestion, perhaps an article such as this one will provide sufficient insight:

http://www.off-road.com/dirtbike/tech/dirt-bike-tech-twostroke-seizure-52428.html

 

[grhonk]

Thanks a ton!

 

[Sportster-2001-951C-Stock]

This article was written by a legondary 2 stroke engine tuner, an actual professional. Search for more of his articles and perouse them, you'll pick up quite a bit about how a 2 stroke engine needs to be tuned and cared for, how they're designed and what's important to know:

www.bridgestonemotorcycle.com/documents/oilpremix6.pdf