RD 350 F2 YPVS Help (now with video)

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Hello,

I recently dug my RD out of the back of the garage and got it MOT'd. I'd recently rebuilt the forks, and the front end feels great. However, the engine seems to be running like crap. When I took it for an MOT they almost failed it on the fact that the indicators stopped working when the headlights were switched on. This was discovered to be a battery problem, so I replaced the battery with a tarty AGM battery. Since replacing the battery the running problem is a bit better... but not fixed. It stuttered around 5000rpm and then would bog down when warm. I assumed the problem was to do with the total lack of electrical power and the fact that the YPVS servo is electric. The powervalve noise is louder and higher pitched now after replacing the battery, and all the lights and electrics work perfectly. There obviously was an issue with the battery, but now that is sorted. But it still doesn't run right!

So, back to the drawing board, I took a look at the plugs. They were sooty, but not too bad. However, I found that the left hand plug cap was loose and no longer clicked onto the plug. So I replaced the plugs and the plug caps, and again the problem is a *little* better, but not perfect.

Now it seems to stutter around 7000rpm, and then when hot it bogs down over those revs. I'd guess it was fuel starvation, but it only does it after the engine has been up to temperature for five minutes or so. Up until then it seems to run perfectly.

Anybody got any ideas what I can check? The bike has been sat for a while, so I might need to clean out the carbs, but I don't really want to do that if I can help it because removing the carbs on this bike is a real pig of a job. Well, removing them isn't difficult, but re-fitting them is! I've also tried running the bike with the fuel tap on prime which doesn't seem to help either.

Help!
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

Its more than likely a "clean the carb, it'll sort it" job.

If it runs like a bag of spuds when warm i'd assume its sort of like my bike when I leave choke on...it just bogs and wants to run like chuff.

Blau Zedong · Banned Joined: 26 Jun 2006 Karma :

If your confident in sparks and ypvs operation then i'm afraids its carb time. Especially the needle jet / pilot circuit. Being stood the carbs are no.1 suspect.
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MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Frost · World Chat Champion Joined: 26 May 2004 Karma :

Suntan Sid · World Chat Champion Joined: 07 May 2009 Karma :

Have you checked out the charging system, coils, Reg/Rec etc.
Seem to have jumped from an electrical problem straight to cleaning the carbs.
How is your new battery now, is it still fully charged?
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Blau Zedong · Banned Joined: 26 Jun 2006 Karma :

MaybeGuy · Super Spammer Joined: 12 Mar 2007 Karma :

If it's stuttering at certain revs and fine elsewhere, it's most likely the powervalve set wrong. Especially if it sounds different.
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MarJay · But it's British! Joined: 15 Sep 2003 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Update:

I cleaned out the carbs today, and I also replaced the knackered fusebox which was held together with wire, and had a household 10A fuse instead of a 15A automotive fuse.

The carbs did have a bit of rust in the float bowls, but I've seen much worse. There did look to be some muck in the main jets, but it came out very easily, and I'm thinking that petrol probably should have got it out...

Anyway, I've not ridden the bike yet since having the carbs off but it still seems to run like a bag of spanners in my quick test... however Ididn't have a chance to fully warm it up, and it did seem to start very easily and idled properly from cold which was a bit of a surprise.

Hopefully if the weather is OK tomorrow I'll find out if I've managed to fix it. If not I suspect the next port of call is to try a different ignition coil. I really really really hope its not a fcuked CDI unit, but then I suppose it would give me an excuse to go for a Zeeltronic...
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

Blau Zedong · Banned Joined: 26 Jun 2006 Karma :

I've never known a CDI go down on an F2, but I've known a stator plate burn out. Annoying because the only way to really eliminate things is by swopping them for known good ones. Easy when your mate owns a bike shop full of dead LC's and YPVS's (which was a privilidge I once had), but a PITA otherwise. Not teaching my granny but did you check the emulsion tubes and associated feeds were hygenically clean?
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18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Old Git Racing · World Chat Champion Joined: 08 Aug 2009 Karma :

YPVS servo motor can go down if you run it without or with a duff battery. Check its working right, watch the cables or take the end cap off and observe as the revs go up, sounds about the revs when its going from closed to open.

OGR
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MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Frost · World Chat Champion Joined: 26 May 2004 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Frost · World Chat Champion Joined: 26 May 2004 Karma :

That'll be fine. I suggest we make the exchange on neutral ground. I'll bring the bike back next week.

What? I don't know where you live? doesn't mat... erm... email me the address. Yes. do that.

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Hmm. Apologies perhaps to OGR, it could be a YPVS problem. I videoed the powervalve pulley when revving the engine and it makes a good attempt at doing its job, but it jumps about as if it's under electrical interference from the engine running. When the engine is off the YPVS cycles fine. When it's running it jumps back and forth in a random way. I think the YPVS motor itself is fine but perhaps the coil is on it's way out and is giving off electrical interference, or the CDI unit is borked. Any thoughts would be appreciated! Oh yeah and I tried running the bike with the YPVS servo disconnected and it was rideable. Not perfect but certainly night and day better than with it connected. The tacho doesn't seem to know what it's doing though and does also jump about randomly sometimes.

Hmm. I vaguely remember reading somewhere that a jumping tacho signifies a borked CDI unit... But I might have imagined it.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

philoldsmobil... · Renault 5 Driver Joined: 18 Aug 2011 Karma :

is it charging?

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

This is what the YPVS does when the engine is running:

https://www.youtube.com/watch?v=dq33cKIksSg

This is the servo cycling normally on startup:

https://www.youtube.com/watch?v=R4QRvI1xFtA

and this is the servo when the engine is running:

https://www.youtube.com/watch?v=Xtkdxh1Mw6Q
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Dodgy electrical connection somewhere. Check the loom plugs and CDI block connector.
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MarJay · But it's British! Joined: 15 Sep 2003 Karma :

I'm told that the powervalve and the tacho are on the same circuit, so the two acting weird could be the same thing. I've got to check the earth from the black wire on the tacho and perhaps run another earth to a point on the frame.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

Suntan Sid · World Chat Champion Joined: 07 May 2009 Karma :

I had a 350 YPVS from new, (the only new bike I've ever owned), and I can assure you that the the power valve jumped around like that from day one, never had any running issues with it! In fact mine jumped around a lot more than that!
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"Everybody needs money, that's why they call it money!" Cool