31K Engine using the 1UA PV Controller

[Off Road]

A couple of months ago, I built a mongrel RZ using
- a 1984 (31K) engine and 84 carbs
- a 1990 (1UA) exhaust, CDI, and PV controller

So far I've put 500 miles on it, and the most notable thing, according to my butt dyno,
is the torque that it has between 7000 and 8500 rpm.
In sixth gear, 7000 rpm (140 km/h), just a slight twist of the throttle, and the bike leaps forward.

Common sense has stopped me from doing any top speed runs on the highway,
but in the lower gears (3rd and 4th), the engine stops making power at about 9700rpm.
Actually, 9700 or 9800 rpm is the maximum rpm that the engine will pull in any gear.

A couple of days ago, I remembered reading that the 31K and 1UA PV controllers were different.

http://www.rzrd500.com/phpBB3/viewtopic ... controller


According to Siverstrom, the fully open rpm of the controllers is as follows:

MODEL - STARTS OPENING @ FULLY OPEN@

31K - 5500 RPM 9450 RPM
1WW - 6000 RPM 10200 RPM

When I was working on another engine, I measured the PV fully closed position, using the zeeltronic.

http://www.rzrd500.com/phpBB3/viewtopic ... hth+height

According to "my" measurements, when fully closed, the PV lowers the top of the exhaust port by 6 mm, on the 31K cylinders.
(Important - I'm not a mechanic. This is just what I measured, and may or may not be correct).

In addition, I'm assuming that the 1UA engine is the same, and the PV lowers the EX. port by 6 mm, when in the fully closed position.


Using this dubious information, I made a graph showing exhaust port high vs. rpm,
for the 31K engine, 1UA engine, and the 31K engine using the 1UA PV controller.




Since my bike is topping out at 9800 rpm, it looks like my PV's are never fully open.
My butt dyno says that the engine likes the lower port height at 7000 and 8000 rpm.
However I think the top end is suffering.

Sure wish I could afford to put the bike on a real dyno, and compare the 2 PV controllers.

[(F5)]

hmm, maybe I should more than skim read, but I get bored & quick results are good results. I choose your CDI. &/or pipes.

- my 1UA would heavily retard the ignition after 9000 & power would sharply fall. of course this was reported as being a few hundred rpm more on the tacho. Peak was like 8700.

A 250RR (Jap model) CDI let the power tail off at a lesser rate, but at 9500 there was nothing doing (on the dyno revs).

[silverstrom]

Don't forget the early controller Steve. There are three controllers, all with different open/close points. The 83/84 controller p/n 29L-85841-00 on PCB, the 85 controller p/n 34X-85841-00, and the 86-90 p/n 34X-85841-01.

I was led to believe that you could tell the 86-90 controller by the blue cable, but I have an 85 controller here that has a blue cable and looks identical to the 86. You have to open them up and check the p/n on the PCB to be sure. It makes a difference.

I tried an 85 controller on my 87 and didn't like it. The 86 controller was much better. Made a big difference actually.

My 87 was rev limited just as your bike is. I installed Carbon Tech reeds and opened up the airbox and jetted up to 210 mains (pj carbs). Went like a scalded cat after that (on stock pipes) and redline was easy to pass and loads of power. No ignition mods, no porting, just cheap and simple stuff. 2smoke has that bike now and I still miss it. It was just fun to ride after the simple mods.

[Bare]

Try to keep your engine below 10k rpms.
ALL forum tales aside, Loadings/ wear increase expotentialy with rpms.
And there is often bugger all power increase past 10 k.. unless heavily modded... in which case constant rebuilds are normally expected as result of the mods/use.
Just my 2 cents

[rdstars]

With the PV Controller you can always mod it with an 8 way dill switch so you can set yourself when you want them to start opening and fully open. Think the biggest restriction you got is the CDI, can always slot the stator to gain some RPM. Ideal would be Zeal.

[Off Road]

Hey Bare. Most of the time I do keep the rpm's below 10K. Honest.
On my track bike, I kept rpm to 9500, when I had it on the dyno, and at the track.
This engine was an unknown, and I'm curious to see what it'll do.

Siverstrom. Thanks for the info on the 85 PV controller.
I happen to have all 3 types in the shop.
83 on the Right, 85 Center, and 90 on the Left.




On my 85 controller, the single wire is Black/White.
My 85 manual says this wire should be Black/Yellow, the same as the 90 controller.

I remember seeing an article on the different types of controllers and how to modify them.
But I can't find it. (If someone has a link, please post it).

I did however find some other interesting info written by Martin Kieltsch.

http://www.rzrd500.com/phpBB3/viewtopic ... 04&start=0

According to Martin:

Programmed curves (0% = closed, 100% = open):

Stock 31K:
5500 0%
9500 100%

Best Test:
5000 0%
5500 10%
6500 40%
7500 80%
8300 100%

So, I graphed the stock 31K PV curve, Martin's PV curve, and My PV curve (31K engine with 1UA PV Controller)





Well, that's interesting.
I thought my bike made a ton of power between 7000 & 8000 rpm.
However, according to Martin, (who's forgotten more about tuning, than I'll ever know),
the RZ engine makes more power if the PV's are opened at a lower rpm, rather than a higher rpm, like on my bike.

At 6000 rpm Martin's PV's are 25% open, mine are 0% open.
At 8300 rpm Martin's PV's are 100% open, mine are 52% open.
That's a pretty big difference.

The 85 Canadian RZ used the 31K engine, just like the 83/84 RZ's.
So, I'm going to "assume" that the 85 PV controller settings are the same as the 83/84 model.
(5500 rpm = 0% open, and 9500 rpm = 100% open).

Since it will only take a minute to plug in the 85 controller, I'm just going to have to try it with the 31K engine and see what the difference is.
If there is a difference?
If I'm perceptive enough to notice the difference?

[2smoke]

Offroad:
To be honest with you, it sounds like your bike is running really good. In totally stock form that's all there is. If you want to rev higher just pull one of those nice aftermarket exhausts off the shelf and pop it on.
You know you want to.

[2smoke]

I forgot, look at the speedo. It only goes to 200!
Tell me what you can do flat out in 6th and I will tell you what I can do.

[silverstrom]

I was sure the 83/84 have different open and close points than the 85. I just can't recall what they are or where on my computer they are. Then again, I'm old and might be making it up too.

Try the 34X-85841-00, and then the 34X-85841-01 if you have one. You'll be amazed at the differences when you compare them like that. Heck, run all 3 to see what happens.

When I put the 34X-85841-00 on my 87 it didn't go well. No top end at all. It was a dog.

It's very likley that no two identical controllers will give the same values. These things are very old and prone to failure. I have controllers here that look perfect and are useless. I've run the controllers from the same years and gotten different results. You really need to do back to back comparrison tests to find a controller that works best for your bike. The zeel sounds more attractive now doesn't it?

[seahorse]

Dam you all. Just when I thought Ill just wack some kennys on and solve my early signing off RZ hybrid, 250 bottom end, and probably 250 controller as apposed to my 31k with some porting and pipes not signing off, Im now back out in the shed to swap the PV's over. Will it ever end. Will I ever be happy. Some wise sole on here said it would never end. Never a truer word spoken. I luv you guy's. It truely never ends.

[silverstrom]

It does end, but only when you run out of money or oxygen, or start another one and strip the current one for parts.

[seahorse]

silence, I wont hear it. LaLaLaLaLa Hmmmmmmm. Seriously good info, having two bikes side by side will be interesting to try out the swap, "if they are different" I guess the covers are coming off tonight. Cheers again, I wish I had something to give back. But I got nothing. Just thankyou for a wonderful knowledge sharing and friendly site. I luv you guys.

[aaronmvrider]

get a zeeltronic seahorse.....

[silverstrom]

Or send your controller off for modification so you can select open/close points at will. A few switch changes and you're good to go. If you don't like it, move some more switches. This mod is on my short list.

http://www.twostrokeracelab.com/

[Off Road]

Tell me what you can do flat out in 6th and I will tell you what I can do.

Hey 2smoke. Let's do that.
When we do the high speed runs, we can film it, put it on Utube and then go to jail.

Offroad:
....pull one of those nice aftermarket exhausts off the shelf and pop it on. You know you want to.

Yes, I have some spare pipes and I have another zeel, so I could bolt $1000 worth of parts onto my $1200 RZ, but I think I'm going to pass.
However, for nothing down and no payments, I will experiment with the oem PV controllers.

Before I go any further, I have to respond to seahorse:

...... Seriously good info, ........... thankyou for a wonderful knowledge sharing ...........

You have me confused with somebody else.
I have no knowledge or experience.
I'm just thinking out loud, and hoping the smart guys will give us their opinion.
Again, I stress, I don't know squat.

So, let me tell you what I learned today.

I found another link to some information written by Martin Kieltsch.

http://www.rzrd500.com/phpBB3/viewtopic ... 04&start=0


Now it gets interesting.
And before people react, I'm not trying to start a fight, I'm just repeating information I read.

On the above link, Martin says that one guy had good success running this PV curve (6000 rpm = 0% & 8550 rpm = 100%)

In the same link, mbsteve says this:

I have been building them for a couple of years now. The area of lot of gain is more in the mid range and some in the top end depending on your setup. You want them to be fully open at a higher rpm's, not earlier. Also you want the YPVS to start opening at a higher rpm's as well.

So some people advocate having the PV's fully open at a lower rpm, and some think they should be fully open at a higher rpm.

And to help clarify/confuse the issue, here's a link to something Kenny said:

http://www.rzrd500.com/phpBB3/viewtopic ... 17&start=0

The highlights are

In the simulator the best open timing is approx 200 rpm before peak power rpm but I do need to verify this on a dyno though.

No I seen this on the dyno on Glyns old bike if we opened it to early then there was a noticable dip in the curve ....

Kenny also said this: (and I like this quote best)

........dont just do what everyone else does do what your engine asks for.

So, different tuners, different engines, different heads, pipes, intakes, ignitions, atmospheric conditions,........and you get different results, and different opinions.
This is the shit that makes modifying/tuning 30 years old bikes, so much fun.

As 2smoke said, my bike is running pretty good, so I'm not about to spend a lot of time or money on it.
But, I'm going to have to try the 85 controller, because really I'm curious to see what happens.

Crap. I typed this up, and before posting, I started searching more stuff.
Found this interesting link on modifying the PV controller.
Unfortunately, the links to the tzr250 forum, no longer work.

http://www.rzrd500.com/phpBB3/viewtopic ... ler+switch

On this link, kenny and slinger give some good info on the PV settings and the CDI ignition curves.

http://www.rzrd500.com/phpBB3/viewtopic ... ch&start=0


And this is were I got side tracked.

Stock curves.

31K
2000=17*
3000=24*
4000=27*
5000=24*
6000=22*
7000=21*
8000=18*
9000=17*
9500=11*
1000=9*

pv setting 5550-9450

1WW
2000=17*
3000=23*
3500=27*
4000=26*
5000=23*
6000=21*
7000=19*
8000=17*
9000=14*
10000=6*

pv setting 6000-10200

Both poop curves

Apparently, the 1UA CDI, (that I'm running on my 31K engine), has less advance than the 31k CDI, and retards the ignition a whole lot, starting at 9000 rpm.
( F5 mentioned this earlier, but it didn't sink in)

I have a spare 29K-50 CDI, and a spare 52Y-50 CDI. (The manual says the 52Y-50 curve is the same as the 29K-50).
Maybe I should install the correct CDI on my 31K engine, before I go playing around with the PV controller.