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315R Engine Knocking


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#1 yam175ty

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Posted 30 May 2011 - 02:07 AM

Hi,
My 2004 315R suffer of engine knocking from 1/8 to 1/4 throttle position or when I cutout rapidly the throttle. I tried to change the jetting and to use VP racing fuel with no results!

Is that your bike has this problem too?

Is anybody have a solution?

Thanks!
Montesa Cota 315R 2004


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#2 copemech

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Posted 30 May 2011 - 03:54 AM

Hi,
My 2004 315R suffer of engine knocking from 1/8 to 1/4 throttle position or when I cutout rapidly the throttle. I tried to change the jetting and to use VP racing fuel with no results!

Is that your bike has this problem too?

Is anybody have a solution?

Thanks!


This is a delorto PHBL carb bike, right? I'm no Mont expert, but I never got rid of that on the Sherco till I went to a #38 pilot jet. What jet do you have now?

Others may have other idears, but? :rolleyes:
Ride it Like it was one of your old Girlfriends, If you still remember how!

#3 yam175ty

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Posted 31 May 2011 - 03:19 AM

Yes it is a phbl bs carb with a #38 pilot. I could maybe try a #40.

Thanks!
Montesa Cota 315R 2004

#4 yam175ty

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Posted 31 May 2011 - 10:57 PM

Finally I'm going to install a Keihin PWK 28 to solve the problem. Someone alteady try this before?

Thanks!
Montesa Cota 315R 2004

#5 copemech

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Posted 01 June 2011 - 02:51 AM

Finally I'm going to install a Keihin PWK 28 to solve the problem. Someone alteady try this before?

Thanks!



Personally, I would try the #40 test first, as it is cheap. Also insure the transition circuit in the carb is not restricted. There are two small holes in the carb circuits, the main idle circuit in the engine side of the bore, and another just behind the slide which is the transition circuit in the range we are talking about. Both feed off the primary jet, yet only the first is metered by the fuel screw. If the second passage has blockage, or the jet is insufficient to support the transition, it will be lean and ping. In reverse, if the primary jet is too rich, it will blubber in the range, as the jet is the determiner, not the screw or needle.

I would have never thought it, but going from the 36 to 38 fixed mine, so just goes to show. This crap drove me crazy untill I figured it out. Add, they all vary a bit.

Yes I gotta run the fuel screw in just a bit at between 1.5 and 2 turns out, so in a more selective range on the day.

A kiehin is a good carb ,but finiky as well and also more power accross the range typically. :rolleyes:
Ride it Like it was one of your old Girlfriends, If you still remember how!

#6 yam175ty

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Posted 01 June 2011 - 02:01 PM

Thanks copemech,
i'm going to try the #40 pilot first and cleaning these little fuel holes.

Thanks :)
Montesa Cota 315R 2004

#7 bikepilot

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Posted 14 July 2011 - 02:36 PM

Hopefully you've solved this by now, but if not... Mine knocked on overrun like that when I got it. I thought it was because I was using pump gas rather than race gas. However that wasn't it at all! Turned out the previous owner had fitted a B6ES spark plug while the bike should have a BR6ES. The lack of the resistor, it seems, was causing all sorts of issues (it also randomly acted like it loaded up and sounded terriable, but was ok if I shut down and re-started). Switched to the BR6ES and it hasn't knocked once since (all stock carb on an '01 Mont). Anyhow, before you try a different carb, make sure you've got the proper plug in there.

#8 nelly1

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Posted 14 July 2011 - 07:02 PM

Hopefully you've solved this by now, but if not... Mine knocked on overrun like that when I got it. I thought it was because I was using pump gas rather than race gas. However that wasn't it at all! Turned out the previous owner had fitted a B6ES spark plug while the bike should have a BR6ES. The lack of the resistor, it seems, was causing all sorts of issues (it also randomly acted like it loaded up and sounded terriable, but was ok if I shut down and re-started). Switched to the BR6ES and it hasn't knocked once since (all stock carb on an '01 Mont). Anyhow, before you try a different carb, make sure you've got the proper plug in there.



i had the same with the b6es changed to an iridium plug and perfect i also cleaned out my exhaust and re packed the silencer dont know if that helped
i got 5 on it




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