Trying to fix an issue
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How long have you been having this problem? Hasn’t been since you last set up the power valve has it
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Since the first or second time I took my carb off to inspect the float valve when fuel was pissing out the overflow
I just took the bike out and I’m certain the powervalve is operating as should be and sat in the right place.
I do however have a sneaky feeling the air boot isn’t properly sealed, causing an air leak.
I’ve also found a little pin prick hole in the carb warmer hose that sends coolant into the carb.
I took the bike out for a little ride, I say little because I got less then ten minutes ago and the temp gauge was already 3/4 across the dash and climbing.
There where a couple times where the bike just shot off like a rocket whilst the valve was pinned but other then that It’d get to about 6-8k (at a guess because remember I don’t have working clocks) then struggle to go any further.
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Did you ever fix the leaky crank seal on the flywheel side, bud? Something still ain’t right if you’re getting that hot. I used to have temp troubles till I sorted out my jetting. Even my bike has been running cool during the worst of the heatwaves. While there is water in the radiator anyways
I’d be looking for any air leaks. Spray on either wd40 or (I use) solvent brake/clutch/carb cleaner. The revs will lower/settle down if it temporarily blocks an air leak...
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@SpookDog said in Trying to fix an issue:
Did you ever fix the leaky crank seal on the flywheel side, bud? Something still ain’t right if you’re getting that hot. I used to have temp troubles till I sorted out my jetting. Even my bike has been running cool during the worst of the heatwaves. While there is water in the radiator anyways
I’d be looking for any air leaks. Spray on either wd40 or (I use) solvent brake/clutch/carb cleaner. The revs will lower/settle down if it temporarily blocks an air leak...
Nope, turned out there was no crank seal. The bike held and made good compression when I did a compression check.
To back this up when I crashed my bike the issue magically resolved itself and the bike suddenly ran beautifully, as good if not better then the day I got it.
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The crank seal failing wouldn’t affect bore pressure. That’s purely between the piston&rings and the head. It would totally fuck with your mixture & running though. It’s such a cheap and easy fix it’d be silly to ignore it. I seem to remember you saying the revs settled down when you sprayed it before?...
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@SpookDog said in Trying to fix an issue:
The crank seal failing wouldn’t affect bore pressure. That’s purely between the piston&rings and the head. It would totally fuck with your mixture & running though. It’s such a cheap and easy fix it’d be silly to ignore it. I seem to remember you saying the revs settled down when you sprayed it before?...
Nah, I sprayed a couple different flammable substances and it made no difference.
And ahh okay
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@Stevie-Wonder
My bad, no worries ... -
@SpookDog
No worries man, I wish it was that, it’d be an easy fix then. But the fact the issue solved itself and ran perfect for a good month after I thought it was that rules out LH crank seal being the problem entirelyIt’s worth noting I tried the old trick of running the bike with the choke on to richen things thinking this might cause stop the heat building and possibly make a difference to how the bike was running.
Unfortunately though this made no difference, temp still carried on soaring and still reluctant to go through the revsThe only place there could be an air leak is where the rubber boot joins the air box… this would then cause a lean running engine.
This leaves me some questions though…
I’m led to believe where the air boot meets the air box doesn’t have to be an air tight unit, is this right?Being a water cooled engine doesn’t this mean as long as there’s sufficient coolant, your radiator and water pump hoses etc are all in good working then even if you had an engine that was run very very lean the heat would be managed?
Or would it be more a case that the cooling system isn’t up to the job to handle those conditions?
As it stands to sort this I have to
- Check there’s enough coolant (I can’t imagine having lost enough to make a difference however the carb warmer pipes are still prone to odd drip or two even when I plugged them so this could have built up over time, always worth checking).
- Check water pump is working
- take zorst off and fit new carb warmer coolant line (as one has a pin prick hole from being nipped by the hose clamp)
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Have you not checked the radiator level yet? I would check that first job. Second would be swapping out the thermostat. Running lean made my bike run ‘hotter’ but not that hot!
Also check for overflowed coolant at the expansion tank filler. Sticky crap below it on the chain guard and swing arm... -
@Stevie-Wonder Air leaks before the carburettor are generally not an issue since you have a carburettor. By that I mean, the venturi effect created due to the air meters the fueling. Since you're only running at normal atmospheric pressures you can rule this out.
With regards to coolant and engine temp, if it's running so lean that the engine detonates then the temperature will spike before/during it seizes. By the time the temperature moves it'll already been too late. You have to keep an ear out for detonation in that case.
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@Stevie-Wonder a lean condition seriously affects the temperature. A main jet 1 or 2 sizes too small can easily make a difference of 20 degrees so an air leak caused by a split rubber can be catastrophic.
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Okay wicked, so we can rule out the rubber boot to the air box not being airtight as not being an issue.
Also the jetting in the carb is the exact same as it’s always been since I’ve had it so jetting shouldn’t be an issue, the only thing that could’ve changed slightly is the air screw.
I’ll keep an ear out for detonation as that’ll give an indicator to wether it’s the engine running lean being the problem or it just being a cooling problem.
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@Stevie-Wonder
Did you check the radiator coolant level?... -
@SpookDog said in Trying to fix an issue:
@Stevie-Wonder
Did you check the radiator coolant level?...Nah after I took it for a ride I just put it back and haven’t touched it since.
Been saying to myself I’d do a little bit here and there after work but this heat has been killing me off and leaving me so fucked where the only thing left to do is have a beer and chill out.
However today I’m going to go through that checklist today and try do as much as I can.
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@Stevie-Wonder Ptsch! What sort of attitude is that! This is perfect trail riding weather. You're young, you should be full of energy smashing it out.
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@SpookDog said in Trying to fix an issue:
Have you not checked the radiator level yet? I would check that first job. Second would be swapping out the thermostat. Running lean made my bike run ‘hotter’ but not that hot!
Also check for overflowed coolant at the expansion tank filler. Sticky crap below it on the chain guard and swing arm...No overflowed coolant. I do have a spare thermostat off a 4FU head I could try too.
@Calum dont remind me
10 hour shifts grafting in 30 degree heat does a number on you though -
And the radiator is full too? If it is then it’s definitely worth trying another thermostat. I don’t even know how many I’ve got in my collection anymore! I brought an old style glass thermometer to check opening temps accurately (only a few £), also to tell me what position on the temp gauge was what, instead of lucky dip!
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Radiator wasn’t full, I have since topped up with roughly half a bottle of putoline coolant.
I’d left to tick over for 10 minutes and didn’t have any anomaly with temp. Gonna take her for a test ride soon. I am hopeful that’s solved it though.
I have noticed a noise that sounds a lot like a bearing of some sort gone in the top end. At first I thought it was just because I had the powervalve cover open that there was more of a raw noise but when you listen I definitely doesn’t sound right
Failing that if a bearings gone that’ll explain a lot!
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@Stevie-Wonder Just watched/listened to your vid. Difficult to diagnose just by listening but I'd say that could necessitate a stripdown to find the cause.
Beforehand though you might want to take a look at the R/H powervalve cover behind the expansion chamber as these have a habit of breaking around the retaining bolt and rattling due to exhaust pressure and the broken bit stopping it falling out completely.
It happened to me once on an RD500LC (it uses the same part x 4) and it made that exact noise. Everyone I was riding with ripped the p!$s out of me because we all thought it had blown up but I rode it 50 miles to get home and just replaced it. Hope that's all it is!
