YZF750 CDI?

[swanman]

I bought my yzf about 6 weeks ago. It is an SP model, Japanese import of 1993 vintage. I have had it on the dyno at Red Baron and 2 things became apparent the ps at rear was 95, and the flat sides have been replaced by CV carbs at some stage.

I reckon this bike is restricted, probably by the CDI box, as it does feel a little pedestrian. Does anyone know about this sort of issue.

I have emailed Gary at GP motorcycles and he reckons he can sort me out on his dyno so long as I have the full power CDI.

So I am looking for a full power CDI where do I look, how do I know it is a full power one(serial no.s?) are there any other things I should know about? What are they worth?

Also what is a good average rear wheel power output for a full power yzf with CV carbs?


Cheers

[White trash]

Have you got a pic of your SP Swan'? Are you SURE it's an SP?

Not doubting your expertise mate, but a friend was suckered into a YZF750SP that wasn't once, and he thought he'd done his homework.

Also, PM F5Dave, he's a guru when it comes to these things I think. Who the hell'd replace the flatties with CV carbs anyway?

[swanman]

Have you got a pic of your SP Swan'? Are you SURE it's an SP?

Not doubting your expertise mate, but a friend was suckered into a YZF750SP that wasn't once, and he thought he'd done his homework.

Also, PM F5Dave, he's a guru when it comes to these things I think. Who the hell'd replace the flatties with CV carbs anyway?
Yes sure it is an SP. Has the close ratio gear box, fully adjustable suspenders. The mechanic at red baron, who seems to know his yzf's, assured me it was an sp with swapped out carbs, which he said was a good mod as the flat sides are troublesome and don't give any more power.

[White trash]

OK. On those earlier Jap imports, the first restrictions are usually in the inlet manifolds. Pull the carbs out and have a nosey down the holes. If it has the stock exhaust system, there could be something in the headers or where it collects into one also.

[swanman]

OK. On those earlier Jap imports, the first restrictions are usually in the inlet manifolds. Pull the carbs out and have a nosey down the holes. If it has the stock exhaust system, there could be something in the headers or where it collects into one also.

Ta, I'll check it out.

[FROSTY]

Jeysus swannie--I told ya that on thursday.
Seriously though mate Heres how the japs restrict em.
restricted inlet rubbers.restricted exhaust ,restricted power curve cdi box full rpm restrictions in top gear.different cam timing

[swanman]

Jeysus swannie--I told ya that on thursday.
Seriously though mate Heres how the japs restrict em.
restricted inlet rubbers.restricted exhaust ,restricted power curve cdi box full rpm restrictions in top gear.different cam timing

Yeh I know.
So I checked the inlets today. When you lift the slide all you see are the butterfly valves, so I guess no rubber restrictors.
Also went to City wreckers yesterday where they have a restricted SP CDI box serial number 4HA-82305-00. Mine is an SP one too serial no 4JD-82305-00. The R ones are quite different, diff plugs. So what does that mean that mine is in fact full power, as the ser no is different from the restricted one?
It was thought that the throttle position sensor may be too blame as the flat sides have a sensor linked to the CDI, but so does mine on the CVs.
That leaves cam timing, which I think unlikely as the CDI units seem to be culprit i.e. restricted or not restricted.
Anoying thing is people keep telling me how quick these bikes are supposed to be, but mine ain't.
I need to ride side by side with SP on his bike to see what the real difference is.

[FROSTY]

mate--the restriction is between carbies and head :devil2:
Ya wont be riding with SP cos he aint got one anymore.

[swanman]

mate--the restriction is between carbies and head :devil2:
Ya wont be riding with SP cos he aint got one anymore.

You mean on the other side of the butterfly valve? (It's obvious I aint no mechanic).
I spoke to Sp on Thurs about a back to back ride and he was up for it. I guess he misunderstood me, must be my accent.

I have now looked behind the buttefly valve, with a torch and there is no rubber there or other obvious impediment.

[F5 Dave]

Didn't see this & mailed you

4HS 82305
(BB7271)

Two big plugs into it same size as each other

If the TPS has different resistance values then it won't operate the same. Might be interesting to run the bike on the dyno & tune the TPS to different values (it's basically a pot= variable resistor).

[Monsterbishi]

Well, I'm just gonna post up here because only a handful of us KB'rs have YZF750's...


Yes sure it is an SP. Has the close ratio gear box, fully adjustable suspenders.

My YZF750R came with fully adjustable suspension as well...

[swanman]

4HA-82305-00 is restricted Sp at City Motorwreckers

4JD-82305-00 is mine an SP

4HS 82305 is Dave's is an SP

I don't quite know where this is getting me, they are all different! AHHHHH!

[scooterboynz]

hey swanny , do you know what ever happend to your old r1? a mate of mine was looking at buying one from red baron , it was black , had a respray , told him it had been in a minor off , so the guy changed the colour to black , my mate did some more investigation and it had a new speedo (so much for the minor off) did more investigating turned out it had been deregistered and revinned , thats what they do to stuff thats been written off , so red baron lied to him , minor off my arse!

[F5 Dave]

Yeah it’s a swine but even though Yamaha are pretty good with standardising of components they do go silly with part numbers. My RZ I wanted a head gasket in a hurry & they had a few different part numbers so wanted a frame number. Course they are all the same but may be for a different year.

With the CDI (technically incorrect name but easy so we’ll keep using it) it could be different markets, either restricted or maybe noise test at different levels, heck I dunno, or it might be they changed the ignition curve in latter years.

Think the only thing you can do is ask Yam NZ to try to clarify which ignitions are restricted (which they would have to ask Yam I suspect).

[swanman]

hey swanny , do you know what ever happend to your old r1? a mate of mine was looking at buying one from red baron , it was black , had a respray , told him it had been in a minor off , so the guy changed the colour to black , my mate did some more investigation and it had a new speedo (so much for the minor off) did more investigating turned out it had been deregistered and revinned , thats what they do to stuff thats been written off , so red baron lied to him , minor off my arse!

No idea wot happened to the bike. I'd be suprised if it was back on the road, but u never know.

[FROSTY]

hey swannie --maybee if ya talked nicely to the new owner of SP's old YZF
he might let ya try his CDI in your bike
dunno mind you I heard he was a shitty bastard

[DEATH_INC.]

hey swanny , do you know what ever happend to your old r1? a mate of mine was looking at buying one from red baron , it was black , had a respray , told him it had been in a minor off , so the guy changed the colour to black , my mate did some more investigation and it had a new speedo (so much for the minor off) did more investigating turned out it had been deregistered and revinned , thats what they do to stuff thats been written off , so red baron lied to him , minor off my arse!
Check out the steering stopper,swannies had been broken off,see if it's been welded. :sherlock: :msn-wink:

[DEATH_INC.]

Ummm,isn't 95rwhp about right for one of these? Allowing for a few years of wear and maybe not a perfect state of tune....

[F5 Dave]

Would have thought about 108 dynojet sized horses if the compression is ok. The changed carbs are still my question point.

[swanman]

Well the new owner of John's old yzf750sp has kindly offered to let me swop bits of his bike out to do side by side tests. So that should nail the issues down. Come on Frosty when are you free?

BTW compression was checked at Red Baron and was found to be fine.

[FROSTY]

swannie--The new owner of SP's bike is awaiting your call
He told me he thinks you're some kinda--Hmm "pommie poofta whos scared to ride a grunty bike"

[swanman]

swannie--The new owner of SP's bike is awaiting your call
He told me he thinks you're some kinda--Hmm "pommie poofta whos scared to ride a grunty bike"

What's your tel numbers again?