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Post by gentile on Sept 24, 2022 13:28:54 GMT
Hello there,
My 1978 ET3 has had a few problems this year and has been sitting around gathering dust whilst I tried to get it seen (unsuccessfully) earlier in the summer. I got bored of trying to find someone to take a look at it so decided to have a go myself...
Earlier this year i noticed that after five minutes or so of riding, starting cold is fine, and running (also fine) that it would start to lose some power in second and third gear. It felt like the carb was blocked and then after a while it would suddenly pick up again for a little bit, but then revert back.
The bike doesn't die it just looses 85% of its power in those gears. I'd also noticed that it seemed to be dropping oil from under the gears.
So, I pulled the carb, stripped it and gave it a good clean. I replaced all the seals with a carb kit and lubed a new washer for the manifold (card side). It's a relatively new carb and didn't appear to be in terrible condition.
I then pulled the tank and cleaned it all out, getting rid of any rust (there was hardly any in it). The spark plug was blackish so I replaced that too.
I also dropped the gear oil (there was hardly any left in there) and replaced it and put new nuts on it.
Today I filled her up and gave the carb a tune and I was happy with the fueling and it sounded great!
So off I went earlier with a huge grin on my face......only to find that the problem remains....after about five minutes 2/3rd gear loses its power. It then picks up enough for me not to have to stop but all that's in mind at that point is getting home!
Any suggestions? I've read about how you should fill the gaps on the carb manifold with sealant on a smallframe. I've got some sealant so i could try that....but do these symptoms seem like an air leak?
Thanks if anyone can help. I'm on the south coast so will be looking for someone locally to take a look at it if I can't sort it out.
I hate being with my Bike I've had it 20 years!
Cheers Gentile
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Post by henri on Sept 24, 2022 16:29:01 GMT
sounds ignition related to me , failing LT coil or pick up on the stator ,or dodgy cdi or connections on it . where on the south coast are you , i'm in brighton .H
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Post by gentile on Sept 24, 2022 16:43:37 GMT
Hi Henri, thanks. We spoke back in April about the possibility of you taking a look but you were very busy.
I was really hoping a carb strip down and clean, fuel tank clean and new spark plug would rectify it but no joy.
I am along from you and hour in Rustington. You mentioned a friend could maybe pick it up last time around in a van. I'd be keen to have it looked at as I am desperate to get it back on the road.
Best Gentile
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Post by jbcollier on Sept 25, 2022 13:23:06 GMT
I agree with Henri but first leave the fuel tank open and see if that makes a difference.
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Post by gentile on Sept 25, 2022 13:57:10 GMT
This might be a stupid question, but do you mean open the tank cap place the seat back down and go for a ride? Will petrol not splash out?
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Post by henri on Sept 25, 2022 17:54:19 GMT
it might , but if the problem disappears JB has nailed it . a blocked breather on tank can cause fuel starvation ,an your symptoms. i missed that , but are colonial cousins on the money. theres also fuel pipe length an routing to consider , but reckon JB's try 1st . start simple eh .H
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Post by tzsteve on Sept 25, 2022 18:13:46 GMT
Lost oil could be from clutch or gear linkage, but could also be a badly fitted case gasket.
Loosing power like most others i would be looking at ignition
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Post by gentile on Sept 25, 2022 20:57:32 GMT
Thanks everyone, I really appreciate the help.
Henri, when you say a blocked breather on the tank, do you mean a blockage inside the tank itself, or the breather is on the way out of the tap down the pipe into the carb? How would riding with the fuel cap open solve that? More pressure forcing for fuel down the pipe with force this solving the starvation?
The oil leak has now gone completely so I think that must have been related to the old seals and nuts that were replaced.
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Post by henri on Sept 26, 2022 5:47:51 GMT
the cap has a hole in it ,if you look at the inside you can see it right in the centre .it allows air in so fuel can flow out ,a blockage or something simple like a rag or waterproofs under the seat .can cause your symptoms .H
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Post by gentile on Sept 26, 2022 6:15:40 GMT
Thanks Henri
I did stick a pin through it so I could see it come out the other side as part of the tank rebuild/clean. Is that enough of a clear out or do I need to make the hold a little bigger?
I'll also try the cap open suggestion too as soon as the weather breaks.
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Post by gentile on Sept 26, 2022 19:57:58 GMT
Just had the tank out again to check the hole in the fuel cap and to see if there was fuel flowing from the tap. Hole is fine and the fuel flowed quickly without any blockages.
One odd thing I noticed when putting the tank back was that I could move the carb from right to left (twist it) but not forward backwards (clamp is on).
Should I be able to move the carb in a twisting motion like that? I'm sat on the bike in riding position and left hand on carb I can twist it to the left. Not far but enough.
I only found this out when attempting to reconnect the fuel to the carb with the tank in and the carb twisted as I placed force on it to put the fuel line on it.
The clamp is very tight on.
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Post by henri on Sept 27, 2022 5:50:55 GMT
it shouldnt be able to move at all , clamps stretch ,or if new arent made well ,an close up on themselves before fully tightening up the carb . take it off an remove clamp bolt ,an then widen the slot with a grinder or hacksaw .H
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Post by gentile on Sept 27, 2022 7:13:03 GMT
Will do, thanks Henri
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Post by gentile on Sept 27, 2022 8:09:05 GMT
Henri, could the loose Carb be a cause of the problems I'm seeing?
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Post by oldscooterbloke on Sept 27, 2022 14:32:44 GMT
Hi, a loose carb is trouble , but usually runs fast at tickover. also the fuel is lean at that point. Just a thought ,watch the fuel pipe routing if its too long and dips low it can cause an air bubble / air lock, had an issue on a large frame until i shortened it , solved
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Post by gentile on Sept 27, 2022 15:50:38 GMT
Thanks oldscooterbloke
I've not long had a new pipe on it. I got one of the clear pipes with the thin wire inside to stop kinks. I measured the exact smallframe length I needed to go from the tap down and across under fuel tap onto carb so there is very little slack in there.
I'm going to work on Henri's advice re-clamp and get the carb seated properly, then I'll give it a run with the fuel cap off and see if that makes a difference.
Failing that....it looks like it will be ignition related I guess....nightmare...
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Post by gentile on Sept 28, 2022 6:32:33 GMT
One more question on the twisting carb.
When I took the clamp off and repositioned the carb I noticed that it wasn't actually the carb twisting on the manifold, but the manifold itself? It doesn't twist a lot probably 12pm to 2pm? So with the carb on and tight you can move it 12 to 2pm but the whole unit moves so it isn't the clamp.
Is it normal for a manifold to have a little give in it?
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Post by gentile on Sept 28, 2022 11:01:06 GMT
UPDATE
So I took the Carb off the manifold and clip and re-seated it. The only slight movement is some twist but it's not the carb moving it's the unit as a whole moving a little.
The last recommendation was to take the fuel cap off and see if the symptoms are still there. I placed some cardboard on the fuel tap to stop if fully closing and just took it out for a ride. No symptoms....just a huge grin on my face.
I couldn't believe it so carried on for a further 10 minutes and have it a fair bit of Welly to make sure it was heated up properly but no more loss of power in 3/4th gear. No more what felt like bogging.
I'm so happy ...but I already put a thick needle through the hole in the fuel cap and I could see it poke out the other end. If the bike is fine with the fuel cap open, does that simply mean I just need to make sure the hole in the fuel cap is bigger? Could there be something covering the hole when the bike starts moving (so when I check it all seems well but when I am moving something covers the hole?).
I feel like I'm almost there!
Cheers everyone Gentile
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Post by jbcollier on Sept 28, 2022 12:30:05 GMT
Great news but still fix your loose manifold!
Hard to say what's up with the breather. Anything stuffed under the seat?
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Post by gentile on Sept 28, 2022 13:44:32 GMT
Under the seat is empty. I have a feeling that the hole may be somehow becoming blocked when I set off and the vibration of the bike is somehow moving something in the fuel cap over the hole? I think I need to take it apart.
So being able to slightly twist the carb and manifold together (whilst it is tightened to the manifold with the clamp) from about 12 o clock to 1 o clock is a big no no...
How would I tighten the manifold? 🫣
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