Derestricting the fizzer

[riffer]

Even since I found out how to derestrict my FZR750R to bring it up to (nearly) OWO1 spec I've been dying to try it. I've started on the process recently and thought I'd share some of what's been happening.

Firstly, there are two types of FZR750R genesis models. The Japanese domestic model, which is restricted to 77BHP, and the USA model, which is 107BHP. I have the Japanese domestic model, and while its not too shabby, the possibility of liberating a few more horses was definitely appealing.

The Japanese model is restricted in the following way:

1. Air intake through the airbox is restricted
2. The exhaust muffler has lots of restrictions in it
3. The carbs have smaller jets
4. The digital ignitor has 5 degrees advance per 1000rpm between 1000 and 6000 rpm, instead of 10 degrees advance per 1000rpm, in the US model

First step - get the sucker breathing better. There are restrictor bungs in the airbox which are easy enough to remove. The air filter has a rubber bung in it. I removed the restrictor bungs in the airbox and replaced the air filter with a high flow one

Second step - remove the restrictions in the exhaust. I was a bit rough with this, and put a large drill down the middle of the exhaust, and drilled a few holes in the back end. Basically tried to get the air going through a bit faster. This was the zero dollar option, as I have spent about $1200 in the last couple of months fixing it after my bin, so Gini has vetoed any more $$ for things like aftermarket exhausts, etc. Obviously an aftermarket exhaust is the best option here...

[riffer]

Third step - sorting out the anaemic fuel delivery.

This was tonight's work. I've been running the bike with step one and two done, and while it's revving quicker, I'm finding I have to nail the throttle to get sprightly acceleration, and there's a flat spot around 6000-8000 (redline 11000).

SIDE NOTE: I'd turned the rubber thingies that join the airbox to the carbies around a bit to see if they fit better as I had a nasty screech on acceleration. It hadn't fixed the problem so I looked at the airbox again. Turns out on the inside of the airbox the other side of the rubber thingies has inlet pipes which point to the inside of the airbox. Turning the rubber thingies around was causing the inlet pipes to not point to the inside of the airbox, which was restricting the air again. FIXED.

I had to pull the carbs out to get at the float bowls, as there's just no room to get at the screws as the frame wraps around and over the carbies.

I discovered when I pulled the carbies out that the rubber that goes between no2 carbie (from left to right sitting on bike) and the inlet manifold is actually partially split. Awful screech found! I will have to replace that part I guess. I must have done that when I stripped and cleaned the carbies last Christmas. Shit. Never noticed at the time.

So I had to remove the float bowl covers to get at the main jets. There was one screw on no2 carbie (obviously my problem carbie) which was stripped but my trusty impact driver had that sucker out no problem.

The jets in the carbies are pretty little - 82.5's on the outsides and 80's on the insides. These have been replaced with 105's on the outside and 102.5's on the inside.

I was pleased to see that the float bowls were still lovely and clean with no mess at all inside them.

The old jets came out easily, and the new ones went in just as easy.

Then it was just a matter of putting everything back together, turning the bike on, letting the fuel pump fill the carbies, checking no petrol was leaking out of the float bowls, and checking that the idle was okay, then putting the tank back on, and starting it up again.

Dammit, it's pissing down here so I decided to come inside and type this and watch Sports Cafe.

But first reactions - the hesitation and miss has completely gone. It's possibly running a bit rich but I will have to see how it performs going over Haywards Hill to Tawa in the morning. It seems to accelerate a bit quicker but that could be because it was so wooly before I started.

The next, and final step will come when I can find (and afford) either a 1989 FZ750 or 1987/88 FZR1000 digital ignitor. The pre-89 FZ750 ignitor will not work as it has an analogue pickup and no electronics to power the fuel pump.

If anyone knows where to get one I would be grateful for the info. My finances are pretty dire when it comes to buying bike parts, but I'm sure there must be some way it can be worked out.

I will report tomorrow on how the bike is running. :spudwave:

[riffer]

Well it started okay this morning, which is always a good sign.

The power delivery is a lot smoother, and there appears to be a LOT more torque, which is probably attributable to my sorting the airbox out.

Power from 6000 onwards (when the main jet is probably starting to work) is much better, and from 9000 onwards with WOT its quite a bit quicker. I will have to watch that so I don't get a ticket.

Overtaking a car on the River Road passing lane I noticed instead of doing about 120 km/h past them, it was more like 140, so its definitely gruntier.

I don't think its giving me all the power gains I would like, but its much smoother and more fun to ride - the power's more usable.

The seat in the pants-ometer reckons its at least another 10-15hp - possibly more (at the top end) I've gotten from upjetting and opening up the airbox.

Now to find that digital ignitor...

[Cajun]

good work celticno6

[Blakamin]

Excellent!!! good to see its a happier bike now!

did you take any pictures of the proccess??

[riffer]

Excellent!!! good to see its a happier bike now!

did you take any pictures of the proccess??
No, too busy actually doing the work.

[Hooks]

Hey Simon .... now all you need to do is give it an old mans tune up and bring her up for a run over the weekend !! Let her lift her skirts and show what's really underneath !! .... be good for ya too !!!

[James Deuce]

Good on you Simon.

I'm gonna be in my Gargre all weekend I think :)

[geoffm]

ERD do a black box for these IIRC. "Wayne Gum - wayne (at) erd.co.nz
Put some silicone on that cracked boot for a temporary repair - an air leak will stuff things up.
Geoff

[F5 Dave]

With the inlet manifolds, they are old, they will be prone it it. With airbox mods you should make sure any entrance to the box is devoid of sharp edges. The entrance hole should be large enough but no need for excessive. On my YZF it is opened to about the size of a slightly flattened fist & I have put rubber edging around the hole. Drilling holes is a bad idea for this reason.

Most likely your emulsion tubes will be ovalised by now. If you pull the carbs again you may see the tubes from the top are worn. This is VERY common with a few miles. Surprisingly few miles on Yams it appears. Check out the Factorypro website & Exupbrotherhood. Sorry I don’t have any spare YZF ignitions, but if you rang Don at Huka Honda he might well have a spare FZR/YZF one in his personal collection. Or he might not.

Sounds like a huge increase on the mains. I would highly suspect you are running rich now. It would be a good investment to throw the bike on the dyno & use their jets to determine what you should be running. Sometimes it is hard to tell. If you have a flatspot, then it comes on -it can feel more powerful, but you are just using more throttle. I’ve fooled myself before with seat of pants dyno.

Sometimes you can seem to tune out a problem by jetting in the wrong area as they do overlap a bit but it gets too rich in an area you didn’t want to change. Read up about the emulsion tubes, it will never atomise properly if these are shagged, & the saving in gas mileage should pay for them.

Also the port on these early 5V are too big & later years they got smaller.

[riffer]

ERD do a black box for these IIRC. "Wayne Gum - wayne (at) erd.co.nz
Put some silicone on that cracked boot for a temporary repair - an air leak will stuff things up.
Geoff
Just got a pm from another kiwibiker a few minutes ago which may fix that pesky old digital ignitor problem. Watch this space...

[Blakamin]

ERD do a black box for these IIRC. "Wayne Gum - wayne (at) erd.co.nz
Put some silicone on that cracked boot for a temporary repair - an air leak will stuff things up.
Geoff


Silicon??? near fuel???...um okay.... one of the things i learnt as a young'en NOT to do!
a bit of gaffer tape maybe....

Celticno6, Cant wait to see the beast in action! might have to ride over your way after the buckets....

[riffer]

Silicon??? near fuel???...um okay.... one of the things i learnt as a young'en NOT to do!
a bit of gaffer tape maybe....

Celticno6, Cant wait to see the beast in action! might have to ride over your way after the buckets....
Let me know and I will have a fresh copy of Faster for you ...

[geoffm]

Silicon??? near fuel???...um okay.... one of the things i learnt as a young'en NOT to do!
a bit of gaffer tape maybe....

Celticno6, Cant wait to see the beast in action! might have to ride over your way after the buckets....

Silicone on the outside of the rubber boot, and only if it is age cracked and not big holes. Well known bodge if you are selling the bike (use black silicone...) It works welll, but not a permanant repair.
Geoff

[Blakamin]

Silicone on the outside of the rubber boot, and only if it is age cracked and not big holes. Well known bodge if you are selling the bike (use black silicone...) It works welll, but not a permanant repair.
Geoff



hmmm.... note to self > no buying bikes off geoffm ;)

[Blakamin]

Let me know and I will have a fresh copy of Faster for you ...

Will at least take your phone number this time...:D :mobile:

[riffer]

Will at least take your phone number this time...:D :mobile:
Hmmm. Hopefully not this weekend Blakamin. I gave my last copy to pete376403 a couple of nights back. I meant to make another one today but got kind of distracted by work commitments.

I'm not at work tomorrow but I will make a new copy on Monday (you never know, your copy might turn up this weekend - only a week late - hooray for fastpost).

I'm working in Tawa on Monday - an chance of you getting out that way?

[Blakamin]

Hmmm. Hopefully not this weekend Blakamin. I gave my last copy to pete376403 a couple of nights back. I meant to make another one today but got kind of distracted by work commitments.

I'm not at work tomorrow but I will make a new copy on Monday (you never know, your copy might turn up this weekend - only a week late - hooray for fastpost).

I'm working in Tawa on Monday - an chance of you getting out that way?

Will be at work on monday...grrr.... we'll sort something out oneday tho!!! :niceone:

[riffer]

Will be at work on monday...grrr.... we'll sort something out oneday tho!!! :niceone:
I'll see what I can do Monday ...

[mangell6]

Are ya gonna get the left rear light fixed or concentrate on the motor, or do I have to talk to the father-in-law :lol:

[FROSTY]

celtic--id budget to buy a new set of rubbers. theyll all be hard as heck.
ill second the silicone on the manifold thing.
my experience with yams -i'd try 100's in the two inner carbs.

[riffer]

Are ya gonna get the left rear light fixed or concentrate on the motor, or do I have to talk to the father-in-law :lol:
Not payday till next week Mike.

and the Father in law hasn't been a cop for many years so I'm pretty safe...

[riffer]

celtic--id budget to buy a new set of rubbers. theyll all be hard as heck.
ill second the silicone on the manifold thing.
my experience with yams -i'd try 100's in the two inner carbs.
Hard's not the word for the rubbers, Frosty. They're shot.

I've got Robin at Sawyers finding some for me.

As for the inner carbs - original Yamaha spec for the FZR750R US model was 105's outer, 102.5's inner.

Do you think it needs to lean out a bit in the inner cylinders? Is that because they run too hot with 102.5's?

I'm really keen to find out more about this, as I feel I've embarked upon a journey which may take me to a rather interesting place :msn-wink:

Sure is good having lots more horsepower...

[pete376403]

Hmmm. Hopefully not this weekend Blakamin. I gave my last copy to pete376403 a couple of nights back. I meant to make another one today but got kind of distracted by work commitments.

I'm not at work tomorrow but I will make a new copy on Monday (you never know, your copy might turn up this weekend - only a week late - hooray for fastpost).

I'm working in Tawa on Monday - an chance of you getting out that way?

Will be able to give you both copies back - theres been quite a saga with this. First copy did not play in either two standalone players (both multizone) or a playstation. Also tried in a Toshiba laptop with DVD. Got the second copy, same as before. Guy at work tried it in his player, nogo either. Took it to a customer site where they have a DVD rewriter (Sony DU510) Did play on that setup, so tried copying the disk, with the intent of recording to a DVD +R. Both failed on the copy to hard drive stage at approx 85%. Another workmate has a DVD rewriter so he is going to try making me a +R copy this weekend.

[Blakamin]

Will be able to give you both copies back - theres been quite a saga with this. First copy did not play in either two standalone players (both multizone) or a playstation. Also tried in a Toshiba laptop with DVD. Got the second copy, same as before. Guy at work tried it in his player, nogo either. Took it to a customer site where they have a DVD rewriter (Sony DU510) Did play on that setup, so tried copying the disk, with the intent of recording to a DVD +R. Both failed on the copy to hard drive stage at approx 85%. Another workmate has a DVD rewriter so he is going to try making me a +R copy this weekend.


Can post to me pete:D dont use freakin fastpost tho....useless pricks :mad:

[mangell6]

Not payday till next week Mike.<snip>

Noticed it when you were over taking cars "legally" who were in the left lane while I was in the right.

[riffer]

Noticed it when you were over taking cars "legally" who were in the left lane while I was in the right.
I make an attempt to ride within the confines of the law at all times Mike <_<

[riffer]

Will be able to give you both copies back - theres been quite a saga with this. First copy did not play in either two standalone players (both multizone) or a playstation. Also tried in a Toshiba laptop with DVD. Got the second copy, same as before. Guy at work tried it in his player, nogo either. Took it to a customer site where they have a DVD rewriter (Sony DU510) Did play on that setup, so tried copying the disk, with the intent of recording to a DVD +R. Both failed on the copy to hard drive stage at approx 85%. Another workmate has a DVD rewriter so he is going to try making me a +R copy this weekend.
Most reliable way to make a copy of this movie is to copy all the files to a folder on your hard drive.

I used Nero 6 (latest version - the one that's compatible with XP Service Pack 2) and selected DVD-VIDEO, copied all the files from the hard drive into the VIDEO_TS folder on the DVD.

I tried to just copy it with DVDXCopy Platinum and DVDShrink and both failed.

I will pop by on Sunday and pick them up. I will send one to Blakamin using a TrackPak from work on Monday.

[mangell6]

I couldn't believe how far you went over taking cars perfectly legally and none of them hugged the centre line, incredible and at rush hour. Vehicles were moving at a respectable pace as well. You should be able to complete this manuver (sp) a lot faster now with the extra hp.