Can this make my 250R knock??

**trikezilla** · 02-09-2006, 09:34 PM

Hey all,

Ok, heres the deal. I am running my 83R at 32:1 with Bel-Ray H1R synthetic race oil. At idle I notice a definate knocking / louder clicking. It isnt a sporadic knock...its very consistent. Never louder and never softer. This is a definate knock and not a "PING". I am not sure how loud it is at higher RPMs as I cant hear it over the exhaust itself (so that means I cant tell if it gets faster at higher RPMS either.)

-Am I running too lean? The plug color is always right.
-Can a lower octane fuel make the engine knock? I am running Regular unleaded....if this is the problem what grade should I use? (see sig for engine mods)
-If I go to 20:1 would the ticking go away you think. Im gonna try it next fill up, but I am curious

-What part(s) failure typically makes a knoinkg noise? Its coming from the tope end (but the engine still makes tons of power). Could this be the piston, connecting rod/bearings, wrist pin worn out and/or its bearings?

Lol, and yes I have read my Clymer about these problems, but I just want more knowledge from people that have actually experienced

Any help is much appreciated

Charlie

**timex69** · 02-09-2006, 09:46 PM

sounds to me like your crank rod bearings are starting to go but thats just me...i know my cr80 ddi that before my rod bearings totally went.

**dufrain** · 02-09-2006, 09:55 PM

Could be piston slap also.Check your compression psi with a guage,You can rent one free at autozone.

**trikezilla** · 02-09-2006, 09:55 PM

As in "crank rod bearing" you mean the bearings that are in the cases right?

The way I understand it: The bearings that actually hold the crank horizontal in the motor went, and then the bearing between the counter balancer went right?

**trikezilla** · 02-09-2006, 09:57 PM

I will maybe look at the compression, but Im positive its good due to the stong power from off the line to wide open. I will run one though before I do take the head, jug, ect. off.

**ChrisD** · 02-09-2006, 10:06 PM

I don't know what to tell you here....my 85R has sounded like a timebomb for the past 4 years. It does have a rattle to it, especially noticable at idle. It would usually go away when you put a load on it.

If your jetting wasn't right, you would hear a very distinctive ping / death rattle under heavy load in the upper revs so it's not that.

You probably have piston slap from your cylinder getting worn or a piston cage bearing that's worn. It might be getting close to time for a rebuild, but I doubt that the rattle you hear will leave you stuck miles back in the woods. The 250R motor has a notoriously loud chatter to it to begin with.

**kloby** · 02-09-2006, 10:59 PM

low octane rating could cause this yes ..... - nodz - i would never run regular unleaded in any powersport playtoy

**BLAZERONE22** · 02-10-2006, 12:29 AM

I've had that rattle in my air R for 3 years now, I thought it was piston slap until I did a topend job on it and it did'nt go away. I was thinking maybe counter balencer bearings.

**3Razors** · 02-10-2006, 01:22 AM

You might try 91 octane and see how it acts.

**trikezilla** · 02-10-2006, 06:57 PM

Ok, next fill up I will go up to 91 octane

Dave: So you redid the topend and it didnt go away? Did you relace everything then? I take it you didnt look at the counter balancer bearings then right?

I dont notice anything odd when its under a load...just at idle like I mentioned. I wish I could hear over the dumb BRAAAAP BRAAAAPP!

Well, I am going to run 91 Octane, mix it at 32:1 ( I made a mistake in the previous post of stating it mixed at 32:1)

Could 40:1 be to lean???

Hopefully I can get it to sound a bit better by changing variables like gas to oil ratios etc. If not Im gonna look at the top end.

Why does a low octane fuel cause a knocking noise??

**mikey's250sx** · 02-10-2006, 07:01 PM

low octane ignites at a lower temperature so it actually ignites while the piston is moving up in the stroke still causing a pinging noise.

i do not believe the oil mix ratio will create or alleviate the knocking noise.

**BLAZERONE22** · 02-10-2006, 08:07 PM

Originally Posted by trikezilla

Ok, next fill up I will go up to 91 octane

Dave: So you redid the topend and it didnt go away? Did you relace everything then? I take it you didnt look at the counter balancer bearings then right?

I dont notice anything odd when its under a load...just at idle like I mentioned. I wish I could hear over the dumb BRAAAAP BRAAAAPP!

Well, I am going to run 91 Octane, mix it at 32:1 ( I made a mistake in the previous post of stating it mixed at 32:1)

Could 40:1 be to lean???

Hopefully I can get it to sound a bit better by changing variables like gas to oil ratios etc. If not Im gonna look at the top end.

Why does a low octane fuel cause a knocking noise??

Yeah, fresh bore, piston, wrist pin, rod beaing was in spec. It more noticable at idle, I had a bunch of guys at the trike rampage take a listen and they thought piston slap. like I said, I think its the balancer bearings but its just a guess until I crack her open.

**freaksfix** · 02-10-2006, 08:22 PM

I have owned about a dozen 250r's,, from 83-87 trike and quad and ive had probly half of them apart... everyone of them had the same noise,,, to this day i still dont know what it is..... im at the point if my R didnt sound like that when i started it thats when i would worry...

**BLAZERONE22** · 02-10-2006, 08:26 PM

Yeah after 3 years I'm not to worried about mine. I have a spare if it does ever let loose...

**250rCRazed** · 02-10-2006, 08:38 PM

Originally Posted by trikezilla

Ok, next fill up I will go up to 91 octane

Dave: So you redid the topend and it didnt go away? Did you relace everything then? I take it you didnt look at the counter balancer bearings then right?

I dont notice anything odd when its under a load...just at idle like I mentioned. I wish I could hear over the dumb BRAAAAP BRAAAAPP!

Well, I am going to run 91 Octane, mix it at 32:1 ( I made a mistake in the previous post of stating it mixed at 32:1)

Could 40:1 be to lean???

Hopefully I can get it to sound a bit better by changing variables like gas to oil ratios etc. If not Im gonna look at the top end.

Why does a low octane fuel cause a knocking noise??

Not saying that the problem has anything to do with pre-mix ratios, which I doubt it does, but just letting you know that 40:1 as opposed to 32:1 would give a RICHER A/F reading. The reason is, for every unit of liquid going into your motor, with 40:1 you'd have less oil and therefore more fuel in that given amount of liquid, creating a RICHER A/F mixture. Many tuners will play with the mix to fine tune jetting, but it is only meant for fine tuning, particularly because trying to lean out the mixture too much 20:1 and further will foul plugs, and you could obviously sieze up your motor if you try to make the mixture too rich with not enough oil. As far as your noises go, I agree that the 250R's are noisy to begin with, my Air R does seem to be noisier than my 86R though. Good luck figuring it out.
-Aaron

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Can this make my 250R knock??