Clank sound in midrange throttle position V1

Minarelli V1, Polini Kit, Pancake Exhaust, SHA 14:12 - 54 main jet

Sounds like rocks are in my motor when I'm above idle but below WOT

I think it's a pre-ignition sound. I've only ridden it for about 5 minutes.

I'm running 87 fuel, 40:1 oil & B7HS Plug.

What would you suggest the next steps be to get it running right?

I'm assuming I should run a higher octane fuel (like 90), bigger main jet? and maybe a B8HS plug to cool things down?

Any other thoughts or tips would be super helpful. Thank you, everyone!

Re: Clank sound in midrange throttle position V1

I see no mention of timing, point gap, points cam cleaning and lubing under flywheel.

Re: Clank sound in midrange throttle position V1

Point gap is about .016. The timing is adjusted to what the paper work said with the kit. I think it's like 22mm btdc. I never lubed anything in the flywheel. What does that entail? Same with points cam cleaning... thank you!

Re: Clank sound in midrange throttle position V1

Right, bigger main jet and premium fuel. With a kit I don't run 87 octane. I just bought 7 gals. of 93 octane and stripped the ethanol out of it.

Make sure the exhaust is clear.(edited)

Re: Clank sound in midrange throttle position V1

Thanks Don! I'm going to pre-mix with premium from here on out and go up on the main jet.

It's starts up, idles & runs great until it starts making that awful noise. Hopefully I will see some progress.

Re: Clank sound in midrange throttle position V1

Hope so,Sean!

Re: Clank sound in midrange throttle position V1

Overpriced Parts /

> Sean Daugherty Wrote:

> -------------------------------------------------------

> Point gap is about .016. The timing is adjusted to what the paper work

> said with the kit. I think it's like 22mm btdc. I never lubed anything

> in the flywheel. What does that entail? Same with points cam cleaning...

> thank you!

That is a must

The points ride on a cam on inside of flywheel just like valves or lifters ride on the cam in a car that must be free of rust and lubed, the pad need to be turned over/ cleaned then oiled

If you don’t service the magneto you will wear out your fiber points follower real quick, the points will close causing retarded timing and loss of spark and you’ll go slower and slower until there’s no spark, Or in extreme cases just sparkless right then and there,

It’s the first thing I ever do to a bike is remove the flywheel and service check everything out, I also inspect what I will say seal and crank end for rus/leakages

This is a puch ignition but all points ignitions are pretty much the same

If you can read my phone finger writings

B4CCBF4B-910C-426A-9630-6956B57C848D.jpeg

Re: Clank sound in midrange throttle position V1

♣Slew Foot♣ /

Sometimes a bearing that's going bad we'll only be a problem at certain RPMs you might want to investigate your bottom lobe on your connecting rod and other crank bearings before it has an explosion

Re: Clank sound in midrange throttle position V1

Thanks everyone for chiming in!

I put 91 gas in it at a 40:1 ratio oil.

I updated from 54 to a 58 main jet.

drove it for about 5 minutes & it's still making that sound at that certain throttle position. I was thinking its pre-detonation because its a knock near the engine. Maybe it's the chain hitting the bike at that certain rpm or something?

Before this I had a phbg & a bigger pipe and it didn't make this noise. (I was even running 87 fuel). Now I switched to the stock carb (14/12 sha) & the pancake exhaust and this is when it started making the knocking noise.

If I can't figure it out I may end up having to replace the bearings and oil the flywheel stuff that was mentioned and go from there. I'm just confused because before it didn't make the noise and after the stock carb & exhaust now it makes it.

Re: Clank sound in midrange throttle position V1

If it's not a loose chain or sprocket or chain guard, make sure the fan,if it has one, isn't broken or loose. Also,that engine mounts are tight.

Then, I'd get an induction timing light and check timing.

Re: Clank sound in midrange throttle position V1

I will check all this easy stuff first. Thanks Don! I did notice the other day that my chain rests on a metal piece of my frame but when I put tension on the chain it lifts off of it. Not sure if my mid throttle range could make less tension and cause it to hit? I will also check engine mounts.

Re: Clank sound in midrange throttle position V1

Sean, before you get on it, the chain can have maybe 1" up to down or less movement. But when yer weight is on it, should have less than 3/4" total up to down.

Re: Clank sound in midrange throttle position V1

Thank you for the info! I never knew about the less than 3/4 sitting on the bike. Thanks again Don, I will work on it this week and let ya know what I find out.

Re: Clank sound in midrange throttle position V1

I sure hope you find the problem. I hope it isn't crank bearings or the clutch drum.

Re: Clank sound in midrange throttle position V1

I never replaced bearings when I got the bike, just the crank seals. So worst case scenario it could be a bearing.

I'm hoping for just something clanking like the chain or flywheel. It seriously is after I just barely let off the throttle once the bike is warm. Only happens at a random mid throttle position not at idle or WOT.

I have a guy in my town that has helped me out with timing and misc things. He still thinks it is pre-detonation. He wants to retard the timing even further to see if he can get it to run cooler and not knock.

I do have a small air leak where the sha meets the intake. Waiting on a o-ring and new shim in the mail. I also ordered some 60 range jets just incase I need to upjet futher.

Fingers crossed I figure it out and it will be something easy. Probably not though..... haha

Thanks Don for all the help! I will let you know what I find out.

Re: Clank sound in midrange throttle position V1

Pre ignition and detonation are two completely different things.

Re: Clank sound in midrange throttle position V1

Clean and gap the points at .014" and then check timing. sixteen thousandths is a little wide.

Re: Clank sound in midrange throttle position V1

Whoops ment pre-ignition. Okay I will adjust point gap slightly.

Re: Clank sound in midrange throttle position V1

You shouldn't be pre igniting unless you have the compression real high, but I doubt you could even start it. Try a cooler heat range plug and maybe upjet a bit. You can maybe try messing with thw different slide cutaways too, seems like more of a carb tuning thing than an ignition if it is directly relatwd to a certain throttle position and not an rpm.

Re: Clank sound in midrange throttle position V1

Yeah, this makes sense. Since the only two things that have changed are the carb & exhaust. I currently have an air leak where the intake and carb meet. I'm sure that's not helping the situation & when it knocks it's always around half throttle.

Just so we are on the same page, it sounds like it's lean in the mid-throttle position causing the knock. WOT is good because the slide is all the way open.

Upjetting and/or adjust the slide cutaway should allow everything to be richer.

The Sha slide I have now has the slight angle towards the end. I think that makes it go slightly leaner from idle? Do you think I order a slide with the flat bottom? I also have seen people put a couple notches in towards the bottom of the angle. Any experience with that?

I have a shim, o-ring & 60 range jets on the way.

Re: Clank sound in midrange throttle position V1

I haven't played with tuning sha slide cutaway, I know they can work, but I cant help you there. Im more of a bing guy. Back to the matter at hand, when you say mid throttle is it more pronounced when its loaded up and you're accelerating at half throttle or is it when you're ripping and then back off the throttle while your still up in the revs. You got the type 2 shim/o ring combo? Nice, that should clean up the leak.

Re: Clank sound in midrange throttle position V1

It does it at both acceleration and deceleration.

If i'm WOT and I just move the throttle down slightly it will clank. Then from idle if I slowly rev the throttle it will clank again at that certain point and then go away the more I rev closer to WOT.

I guess a video of it might help...

Also thanks for taking your time to help me out!

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