250 51L Ignition/Power Valve curve

[toddo]

Hello

I have just got my 85 RZ 250 51L registered and was using a zeeltronic with the standard 31K 350 ignition curve from a canadian 350 workshop manual. I tried a couple of slight variations as it is not running quite correct untill about 5000 RPM and I am not wanting to do any damage. I have read on this site that the 350\250 YPVS curves are fairly close however I am certain threre would be some differances. I understand if anyone is reluctant to share any information on this topic but does anyone know where to find a standard 250 51L graph so I can start ruling out whats not right. 
My searches on this site only really find info on the 350 ignition and power valve curves. 

Thank you!

Todd  

[midlifecrisisrd]

I don't think a slight difference in the curve would cause a running problem

Unless someone has went to the trouble of strobing a 51l I don't think there is any info out there

I know all the bother I had with my 250 ypvs was all down to carbs

Steve

[toddo]

Jan 24, 2022 9:48:55 GMT 1 midlifecrisisrd said:

I don't think a slight difference in the curve would cause a running problem

Unless someone has went to the trouble of strobing a 51l I don't think there is any info out there

I know all the bother I had with my 250 ypvs was all down to carbs

Steve

Thanks Steve!

It may be a carb problem-I was hoping to plot an identical curve to rule out the timing. I am just running the standard 1GA carburettors 
with the same size jets and settings prior to the 1mm over size rebuild.


Todd 

[JonW]

Todd, I would think the 86-on 350 curve would be similar to the 51L as that bike got the 51L style updates in 86. But I do not know for sure.

Have you spoken to Ed Erlenbach? He is the fount of all knowledge on the 250s as he gathered a huge amount of data at one point and he may know the answer. If you do find out please do post it on here, i doubt anyone is trying to keep that info to themselves these days.

[toddo]

Jan 25, 2022 0:53:55 GMT 1 JonW said:

Todd, I would think the 86-on 350 curve would be similar to the 51L as that bike got the 51L style updates in 86. But I do not know for sure.

Have you spoken to Ed Erlenbach? He is the fount of all knowledge on the 250s as he gathered a huge amount of data at one point and he may know the answer. If you do find out please do post it on here, i doubt anyone is trying to keep that info to themselves these days.

Thanks John!

I will try tracking down Ed Erienbach and post anything interesting I find. I was reading some older posts on this site and I think it was someone with a dyno business who was tight lipped about sharing curves.

[JonW]

I think if youre creating curves for customers and you invested time and effort into that then its your IP and I can see why someone would guard that. I would too, especially if a customer or I paid for that work to be done and it was reusable.

The OEM curves should be nothing secret I would have thought, they dont offer much clever as they are safe maps for longevity rather than power.

[toddo]

Thanks john I am sure that was the reason for the secrecy. I found Ed Erienbachs web site which is quite interesting (He credits you for info on the 51L porting)
I am finding alot of info on the 350 ignition curves and TZ on the internet but there is little on the YPVS 250. I think I might wire up the my original 51L CDI to rule out carb settings or anything else but my PV controller is faulty so I will have to figure something out.

[JonW]

Ahh Ed is a nice man, he is too kind.

Do drop him an email as he may have the info, but it isnt easy for him to get 51L stuff as he is in the USA and that market never got any 250, let alone a fast one lol You can say that you asked me and I didnt know and that I suggested he might have the info etc.

If you have the original CDI its worth using it and seeing what is what.

Another option is to try and find a later 3hm curve and look at the TZR250, the 3hm is not a 51L or even close (no extra port) but the TZR might offer some insight? Ive seen TZR CDIs fitted to some Japanese imported N/F2s here.

[toddo]

Thanks again John

I will send Ed an email and look into the 3hm TZR250. It seems a little better after lowering the mains needles but it seems to hit a flat spot around 6000 RPM which is shortly after the power valves are starting to open so when the weather clears up I will have another look at it. I will be content with more or less the standard settings. I have built a jaycar programmable ignition and fitted it to a QT50 to learn more about advacing and retarding timing with 2 stokes and have already managed to mark the piston with detonation marks and am really trying to avoid the same with the RZ.

Regards

Todd

[bare]

Doesn't a Zeel come Preloaded with a 31k Curve these days?
Beyond that IMO it's your PV that are the problem.
A programmable (zeel) PV is Priceless as the Opening and Closings of those valves has Large effect
on both Power And rideable power delivery.
Yama stock ones are best described as mediocre and if the controller is dying, as most eventually do ?
There is a problem.

As in careful PV control setup (careful trial and error experimentations Or dyno time) gives hp and can totally eliminate flat spot problems.
G luck.

[toddo]

Jan 29, 2022 18:49:39 GMT 1 bare said:

Doesn't a Zeel come Preloaded with a 31k Curve these days?
Beyond that IMO it's your PV that are the problem.
A programmable (zeel) PV is Priceless as the Opening and Closings of those valves has Large effect
on both Power And rideable power delivery.
Yama stock ones are best described as mediocre and if the controller is dying, as most eventually do ?
There is a problem.

As in careful PV control setup (careful trial and error experimentations Or dyno time) gives hp and can totally eliminate flat spot problems.
G luck.

Thanks Bare

My zeel did not come preloaded with the 31K curve only the curve on a graph that I programmed in. I will be  experimenting with the PV today. The table for the 31K PV shows the PV opening at 5500 RPM progressively to 10000 RPM.

Todd

[Edd]

Hi Toddo

From my experience with Zeel ignitions the PV part of it does help to clear mid range issues. Not sure how well you know the zeel? Check your static angle if the 250 flywheel is diffrent to the 350 but i dont think they will be the lobes can be in diffrent places on the flywheel no harm in checking as this angle is the basis of the whole ignition curve. Then calibrate your power valves make sure they are open on both sides and set in the zeel. With the zeel the close position can be set to be more or less than the stock cdi. You can play with this setting to get the correct exhaust port opening on low rpm when the power valve remains in the close position.

Regards

Edd

[toddo]

Thanks Edd

I checked with a timing wheel and my static position is 34 degress. My PV cables have been repaired at some point and my fully open and closed positions are 615 and 343 instead of the presumed 240 and 512 for the PV servo motor. At fully open 612 (valves flush with top of port) I deducted 272 (differance between 512 to get 240) from 612 (full open) and this determined my closed position as 343. I am not sure if the fully lowered point is identical in the 250 and 350. I have seen that 51L has a unique CDI box as does the 29L.
I have only ridden the bike when it was down on compression prior to this rebuild so I am not sure exactly what to expect in the lower rev range but it does seem a bit sluggish.
I will keep carefully adjusting settings I tried it with the PV constantly open and it did not seem to bad except a surge in revs between 7000-9000 RPM.

Regards

Todd

[midlifecrisisrd]

The 250 ypvs does not have a lot of bottom end

Under 5k it feels how I remember a 125 feeling like. Over 7k it's an absolute hoot 😀

Steve

[abar121]

That sounds very different to the R1-Z 250. Mine had a lot of midrange (compared to a 1KT/2MA or TDR), but was all over by 9k.

Good fun!

[midlifecrisisrd]

Jan 31, 2022 10:51:45 GMT 1 abar121 said:

That sounds very different to the R1-Z 250. Mine had a lot of midrange (compared to a 1KT/2MA or TDR), but was all over by 9k.

Good fun!

It wasn't that it didn't pull from idle to 5k as it did

Would pull and rev cleanly but not like a 350

Was a lovely little engine

Steve