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mlcjot

New member, bought an old Sherco

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55 minutes ago, mlcjot said:

Nebulous: The reeds all look fine. I'm not familiar with 2 strokes really, so am unsure if the reeds should always be slightly open, or if this is a fault.

I don’t know myself. I’m just helping as best as I can with my limited knowledge , and the odd thread from here. I would have thought that someone would have said by now - so I share your frustration. I don’t know about reeds either. They say leave this , touch this - then when you ask a question and try to pin them down to specific info , they all disappear. Then someone comes back with another comment on something else. Drives you bonkers. Especially when it’s 11pm.   My way of working , is usually to find the factory settings and return there if possible - using standard equipment. Then I get to learn what’s happening - then I tweak and mod it , in the way I want it to work.  I’m sure that’s how everyone here does it too. If only people were more open and spoke the language of on/off specifics - then the less-experienced could learn quicker , and spend more time on the foot-pegs.  But I’ve given you what I can of what I know - and what my common-sense tells me when diagnosing my cars.  Anything else would come from thread and workshop-manual searching - something I’m not bad at , but I’ll put my hands up and say that I lack the specific experience needed in this case

But if I were starting though  - I’d use less than a 37 pilot jet. I would use a 36 or 35. But it’s negligible.  I would use specifically a 118 main. That screw would be 1 and 1/2 turns out to begin with from the factory.  But 3 turns out is the most common setting here? The  needle , out of the 4 possible positions - should be on one of the middle two for UK use. If the reeds are undamaged - I would ensure they are fitted correctly.  Then , logically - it should be down to leak-testing and opening that screw. Any more than 4 turns needed would indicate either wrong jetting size or a fault elsewhere (Seals?). Float height must be 18.5mm - since surging can affect jetting.  I think Copemech covered all that already , but not the float-height spec.

 

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Of course , compression will snap the reeds shut to an extent. Don’t think the Sherco reeds can be “turned” since they have markers.     Cracks can occur in the thick gasket/base plate. These can at least be temporarily fixed with sealant for evaluation purposes.

Must stress the importance of carburetor float-height though. Everything stems from that.

Edited by Nebulous

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5 hours ago, mlcjot said:

trapezeartist: Yep I'm not too concerned about the clutch drag! Totally liveable.

Nebulous: The reeds all look fine. I'm not familiar with 2 strokes really, so am unsure if the reeds should always be slightly open, or if this is a fault.

copemech: I'll revisit the fuel screw when I get back to the bike. Good point about the heavy flywheel, makes sense! Should the reeds always be slightly open? For engine idle speed perhaps?

Thanks!

reeds may not seal perfectly , yet when under backpressure they will !

it needs more fuel, most all dellortos run maxed at 3.5 turns

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Nebulous: I appreciate your frustration on my account, but really I love the discovery and the learning and I've had so much helpful input since I posted here two days ago. I'm finding the trials community to be very helpful and welcoming! Thank you :) That video suggests that I should replace the reeds, I'll verify correct float height and put it back together for a test run, and then look at ordering some reeds.

copemech: Roger that, I'll be winding out the fuel screw when next starting her up. Thanks!

I found a Spanish website that seems to have old parts in stock, has anyone had any experience with www.endurorecambios.com?

Have a great weekend. The sun is shining in south-west Ireland!

Edited by mlcjot

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Cool.  Yeah set float height , pull that screw out a little - and get some fresh fuel in there.   At least ride it for the weekend. Old reeds won’t hurt for a while.  Plenty of British suppliers for Sherco bits. 

The bike itself looks in good nick.            Me - I’m still waiting on ebay , for tiny spanners to do my valve-clearances.  

Edited by Nebulous

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The reed valves should be closed with no gaps that you can see daylight through. Initially remove reed valve and ensure it’s not bent or distorted. Refit carefully to the block. Have you made sure the throttle slide can move freely up and down? By the sound of the engine and the age I would be looking to change those crankcase oil seals anyway, lube the lips of the new ones with either 2T oil or silicon grease sparingly if you will, the seals allow crankcase compression to escape taking with it some of the fuel and air, on revving up and then shutting down the seals allow air to be sucked into the crankcase which lets the engine run too fast for too long back down to idle. While you’re in there you can check the main bearings for excess carbon which does get in and cause frictional losses and eventually failure. From the sound of the engine on the video it is ok 👍 mechanically, but it’s easy to make sweeping statements. By doing the work you will become more confident in the bike and know your way around so if it stops miles from anywhere you may have a chance of fixing it.🙂

Edited by section swept
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6 hours ago, Nebulous said:

Cool.  Yeah set float height , pull that screw out a little - and get some fresh fuel in there.   At least ride it for the weekend. Old reeds won’t hurt for a while.  Plenty of British suppliers for Sherco bits. 

The bike itself looks in good nick.            Me - I’m still waiting on ebay , for tiny spanners to do my valve-clearances.  The radiator fins are anything but straight - and the last guy set the bike up for foot-deep mud.  The Tony Bou prancing-machine I was expecting is doing it’s best impersonation of a BSA B40 at present.  Definitely sad when you can’t even ride the thing - due to a stupid 50p spanner. Been a week now. The supposedly tried and trusted machine I bought to take down the drive and mess about with on a patch of grass - has turned into a high-maintainance Diva with no economic end in sight.  Started looking at other bikes now - that’s how desperate I’ve got!

What bike is that? 4 stroke I'm guessing. I'm much more familiar with 4 strokes, altho I probably only know enough to be dangerous, not to actually fix anything :-) 

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5 minutes ago, section swept said:

The reed valves should be closed with no gaps that you can see daylight through. Initially remove reed valve and ensure it’s not bent or distorted. Refit carefully to the block. Have you made sure the throttle slide can move freely up and down? By the sound of the engine and the age I would be looking to change those crankcase oil seals anyway, lube the lips of the new ones with either 2T oil or silicon grease sparingly if you will. While you’re in there you can check the main bearings for excess carbon which does get in and cause frictional losses and eventually failure. From the sound of the engine on the video it is ok 👍 mechanically, but it’s easy to make sweeping statements. By doing the work you will become more confident in the bike and know your way around so if it stops miles from anywhere you may have a chance of fixing it.🙂

Cool, I'll order some new reeds. There is quite a bit of light showing through. Then, if still no joy, I'll address the crank seals. Do you know what thread pitch I need for the flywheel puller?

I'm loving working on it so far. So simple! :-)

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You may find that with the crankshaft nut released and a bit of gentle wiggling and inertia persuasion that the flywheel may come lose. The best method though is to use the correct tool. I don’t know the thread size but I’m sure you can get a puller for about £10-15 which is a good investment.

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16 minutes ago, section swept said:

You may find that with the crankshaft nut released and a bit of gentle wiggling and inertia persuasion that the flywheel may come lose. The best method though is to use the correct tool. I don’t know the thread size but I’m sure you can get a puller for about £10-15 which is a good investment.

I have a few sizes so will see how I get on. Probably have to buy one though!

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1 hour ago, mlcjot said:

I have a few sizes so will see how I get on. Probably have to buy one though!

Refer to my earlier post on page 1 for the puller-size.  Very common size anyway.  If the crankshaft has any waggle on it - then it isn’t worth putting new seals in until the bearings are done as well. Hopefully it will be ok though.  Pay attention to that little woodruff-key - don’t lose it!

Edited by Nebulous

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22 hours ago, Nebulous said:

Refer to my earlier post on page 1 for the puller-size.  Very common size anyway.  If the crankshaft has any waggle on it - then it isn’t worth putting new seals in until the bearings are done as well. Hopefully it will be ok though.  Pay attention to that little woodruff-key - don’t lose it!

Thanks again Nebulous for your help! Your 4t sounds like a bit of a pain. Are the valves shim under bucket type? Or tappets with lock nuts?

I noticed that the Sherco guide says to run 80:1 two stroke mix. Im not one to go against manufacturer's instructions but would have thought it would be more like 50:1. What do you all run? Thanks 

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1 hour ago, mlcjot said:

I noticed that the Sherco guide says to run 80:1 two stroke mix. What do you all run? 

That would apparently be Maxima K2 at 80/1.  The only oil used by the American distributor for Sherco.

That’s 12.5ml per litre.  Be wise to get hold of a syringe to measure accurately.  I would say that a shot-glass full (25ml) is sufficient for 2 litres of fuel - but Irish shots are bigger!

I have tappets with locknuts. Only pain is learning how best to rotate the crank and keep it where I want. I’m thinking lift rear-wheel , rotate in gear - then lock rear-brake. Be easier with 2 people for sure. But it will be fun learning - even if I have to do it a few times!

Edited by Nebulous

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Thank you both!

Tappets are way easier, you won't have a problem. Finding TDC compression isn't  hard either. Select top gear, rotate the back wheel forward until you see the exhaust valves open and close. Keep going til the inlets open and close, then put a drinking straw or a pen in the spark plug hole and rotate the back wheel until the straw rises to it's highest point. If you miss it and the straw starts to go back down, no biggie. You can rotate the wheel backwards to bring the straw back to the highest point but generally I just go around again.

Edit: once you've found TDC you generally don't need to do anything to lock the crank in place. You can if you want, but nothing is gonna move really. The crank will stay in that position, it isn't under any strain to find a different position.

Edited by mlcjot
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