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Discussion Starter #1 (Edited)
Bought in November in questionable condition. Spent the last 10 weeks pulling everything apart, had frame repaired and coated, installed new cylinder studs, fixed wiring, cleaned up tank, set the valves, undid decades of questionable repairs and errors, etc.

This weekend I finally got a plate, and started some test rides to sort out the carbs. I had an ongoing issue where the idle would either hang hot or cold, or die when hot. But it was great once on the needle and mains, so I rode 100km to work and back, with a few stops to fine tune the idle mixture screw. I thought I had it dialed once I got there.

On the way back in the rain, things slowly started getting worse again - this time, bike would die when off the throttle. Suspected maybe fouled plugs, maybe choking one cylinder due to the carb synch screw being off, maybe ignition issue due to water or something. I could keep things going if I kept the throttle on a bit, it was raining, dark and cold, so I rode home.

Opened the air box to find this




Oh no.

The lid was on properly, but I think the clamps are a bit weak. There are marks on the tank so maybe the tank was pushing on them, either way it obviously lifted enough for it to fill with crud and sand from the front wheel.

I had some hope at first that the rubber snorkels had kept most of the sand out of the engine, but then I pulled the plugs. I'm pretty sure I can see scratches in the cylinder walls and some grains of sand on the vertical piston. The horizontal cylinder looks better (at least viewed through the plug hole), but the plug was oily. It had been dry when I last checked it 100km before while at work.


I'm pretty deflated. I guess I could do compression/leakdown first, cranking it with the starter I feel like it has lost compression for sure, but maybe it's just my imagination.

The engine will obviously have to come out again even just to make sure no sand is left in the cylinders. Then I'll see what the damage is. I was planning to save this years bike budget for some FCRs, now I may be looking for a donor engine instead.


And my neutral light stopped working, too.
 

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The rubber lip on the air filter should have prevented all that crud from getting into the air box. What kind of air filter were you using,I don't see one in your pic?
 

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Discussion Starter #3
I'll take a photo. You are correct though, the aftermarket filter is the problem. It has a rubber lip but I compared it with a picture of the OEM one, and it is much thinner. Meaning the air box lid sat lower. This explains why the clamps were weak and required tweaking to hold the lid down. Looking at a picture of the stock clamps, they had already been significantly tweaked before.

This is another example in a long list of wrong parts that were on this bike when I got it, unfortunately I didn't catch this one. I wonder how long it ran with the filter like that before I got it, the cylinders looked good when I did the studs. Then again I doubt they ever rode in bad weather so the front wheel wouldn't have sprayed dirt up there nearly as much.
 

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Unfortunate

The stock airbox is very effective, I used a K&N with success. Most take snorkels out, I did and loved the intake roar.

The filter/intake should not pass dirt nor sand if properly installed.

Bob
 

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Wow that is a real bummer.

Hard to believe that much crap got sucked into the gap... it's a long path from the road around the fender through the fairing to the top of the engine...do you have a fender on the front wheel? On my SP whenever I pulled the fairings there was no road dirt higher than knee level, mostly it collected at the bottom a bit. My airbox area was always pristine. Having said that I never rode it when there was a lot of winter sand on the roads...

Looks like as good a time as any to go with upsized high-comps.

As for aftermarket filters, I did a lot of research when I bought my current MS and decided to stick with OEM. I've run the oiled K&N's on other bikes, but the fact is they stop less dirt from getting through... a lot less... than the OEM paper filters. I hate paying $70 at the dealership for one, but I do it. FWIW, the K&N seemed to fit about the same on my bike as the OEM... it was a very tight fit and you had to push the clips hard to close them.

Coombs is outside Parksville on the island, right?
 

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Discussion Starter #6 (Edited)
Yes just behind Parksville.

I have the fender on there.. I rode through a lot of water yesterday night on the highway going home, so probably the worst case scenario for water spray. And the roads are still dirty because it's January..

If the cylinders are damaged, which I am expecting them to be, I will go 94mm with high comp.

It already has some nice FBF 11:1 92mm pistons, which are probably wrecked now as well.

I feel pretty dumb for not having changed that air filter, it's just that the PO said it was new, and it looked very clean, so I never gave it much thought. I should've known by now that every part on this bike should be suspect and probably wrong. For example my oil cooler was held on with a butchered SAE bolt on one side and metric on the other. When I turn my headlight to low beam, the high beams turn on and vice versa. The jets were mixed up, the chain too short, and so on.



If the damage is as bad as I am guessing based on oily plug and loss of idle, I'm gonna probably tear the engine right apart and do the oil gallery plug and everything else I didn't get to, maybe some fresh paint..

One thing I still need to decide is if I want to sell my other kidney and put FCRs on at the same time now, and get away from the airbox altogether.
Due to the frame repair there is an extra tube behind my steering neck, which means I have to split the airbox every time it comes off. Huge pita. The only thing is that pod filters are probably also not great in the wet I'm guessing, or is there a good workaround for that?
 

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If the damage is as bad as I am guessing based on oily plug and loss of idle, I'm gonna probably tear the engine right apart and do the oil gallery plug and everything else I didn't get to, maybe some fresh paint..
Well, you still have a couple of months of crap weather until "real" riding season starts. Did you see any metal filings on your oil screen that would indicate that the plug is backing out? I never did on mine in many years of use. It's a lot bigger job than swapping pistons but if you're worried about sand in the bottom end I guess it's gotta' get done.

What a mess.
 

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Discussion Starter #10 (Edited)
i'd stop with the wildly despondent speculation and give it a leakdown test. that way you'll know if it's bad. they're a lot more durable than many think, and the nikasil is very hard.

Yes I hope so. I'll have a compression tester here in a few days. I haven't dropped the oil yet, I want to do the compression reading first.
If it's good there is still the question of the wet spark plug, and the fact that it wouldn't idle, but I guess a lot could be wrong with the mixture and everything if the airbox lid is half coming off and water is being sucked in. Or the ignition for that matter, riding in a rain storm.

What would be the expectation just for straight compression with 11:1 pistons? 150psi or so? I don't have air at home, but if it comes out on there, I'll take it into work and do leakdown as well.
 

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Excepting the sand in your airbox, most of the time idling/fuel/carb issues on these bikes are usually misdiagnosed ignition issues. Fuel and ignition issues often present the same; people are overconfident in their 20+ year old electronics and turn their suspicions to bad gas or their carb's of being dirty or poorly jetted because that's always how you diagnose a bike with carbs.

This sounds precisely how my bike misbehaved when one of the Kokusan boxes died, and again a year later while I spent 6 months trying to find out that my brand new aftermarket coil was bad because I replaced everything associated with my ignition when I replaced the Kokusan.

That you were having issues prior to this means ignition might still be suspect. The OEM coils don't usually go bad, most of the time it's the Kokusan ignition boxes or dodgy plug wires and troubleshooting is done by methodically swapping individual components from one side to the other until the condition moves with the component. You've probably put it together by now, but the ignition and fueling on these bikes is stupidly simple - the two cylinders function wholly separately from each other, like two singles mated only at the crank and throttle cable.

Obviously due diligence is needed for the dirty airbox. But as has been pointed out, these are very resilient motors and all may not be lost.
 

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leak down first !!!!! when the time comes get rid of those stock coils (install Dyna coils ) and up grade your battery cables (Motolectric -) the two easy to fix weak spots on the older machines , my 2 cents
 

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Yes I hope so. I'll have a compression tester here in a few days. I haven't dropped the oil yet, I want to do the compression reading first.
If it's good there is still the question of the wet spark plug, and the fact that it wouldn't idle, but I guess a lot could be wrong with the mixture and everything if the airbox lid is half coming off and water is being sucked in. Or the ignition for that matter, riding in a rain storm.

What would be the expectation just for straight compression with 11:1 pistons? 150psi or so? I don't have air at home, but if it comes out on there, I'll take it into work and do leakdown as well.
First, allow me to qualify myself because I'm new here. I'm a mechanic with 30 years experience on cars and a few bikes, mine and others, mostly European. Theoretical compression is calculated by multiplying the compression ratio by barometric pressure at sea level which is 14.7 psi. So, 14.7 x 11 = 161.7 psi... theoretically. You'll never see perfect numbers, but as you stated, around 150 psi would be normal, maybe a little low with an engine that has some normal wear. Comparison between cylinders is the indicator. If you see 10 psi difference between cylinders it's an indication that something isn't right.

As others have stated, check out the ignition system for faults. Hope everything is fixable without having to do a a tear down.
 

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Discussion Starter #16
Thanks a lot everyone. The initial shock of seeing all that sand under my filter has worn off and I'll go at it step by step as planned. Just need to find an adapter for a 12mm spark plug to the air fitting on the aviation leak down tester we have at work. I'll have a compression gauge at home shortly, so I can do that first to get a rough idea if anything is amiss before I haul it to work.

And yes I guess the ignition system could easily cause the poor idle and wet plug too. Maybe combined with some water ingestion, plus wet motor...

I was just about to order an ignitech box before this happened, so if the mechanical part checks out the ignition system will get a complete overhaul with cables and coils too.

I have the motolectric cables on there already but I do need a new battery as well.
 

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These are the sweet lessons of life, learn them well grasshopper.

As you age and your wisdom grows, trust that you won't make these mistakes again.

If you're already old and you did this, well I think the "wisdom" ship has sailed. hehehe >:)
 

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Thanks a lot everyone. The initial shock of seeing all that sand under my filter has worn off and I'll go at it step by step as planned. Just need to find an adapter for a 12mm spark plug to the air fitting on the aviation leak down tester we have at work. I'll have a compression gauge at home shortly, so I can do that first to get a rough idea if anything is amiss before I haul it to work.

And yes I guess the ignition system could easily cause the poor idle and wet plug too. Maybe combined with some water ingestion, plus wet motor...

I was just about to order an ignitech box before this happened, so if the mechanical part checks out the ignition system will get a complete overhaul with cables and coils too.

I have the motolectric cables on there already but I do need a new battery as well.
Check how firmly your plug caps are attached to the leads. Give a good tug on the caps (off the plugs) - they should stay attached. If not, cut back about 1/2 inch of lead, and screw caps back on (the core wire of the leads corrodes and wears away over time). I spent too much time effing around with my carbs, when it wasn't them... ... it was the plug caps. :(
 

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Stock carbs are very prone to carb icing, ask me how I know. We have a 95' SS (its my wife's bike) with stock carbs. I had to fit a carb heat kit to keep them from freezing up even in the summer during highway rides in the rain. The ultrafine road mist/spray would get into the carbs and freeze. We could ride in the rain as long as we were not in traffic. One more issue for you to rule out and an easy fix. I do have another carb heat kit, if you can't find one. Its for a Monster so it will take a bit sorting to fix it to a SS, but it will work. You need to relocate the oil cooler to the top of the head and make a couple of oil lines.
 
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