Project ‘89 FZR250r 3ln1

OK, tip for you Joker had an issue with his 3LN? after putting a keyster kit through his carbs - the inside pair kits -v- the outer pair kits had the wrong main jets in them - this had previously been noticed by @my67xr - it's wrong on the boxes

His bike wouldn't rev out properly either - I'm sure we get weird looks at being so pedantic about 'bloody fizzer carbs' but they are finicky and need to be set correctly

Some discussion took place, connections were made and we realised that the same error had caught him out

Now, this much is certain, the inner pair because they intake warmer air, which is less dense run leaner, SO the inner pair of carbs get the smaller main jets AND the outer pair, because they intake cooler air, being cooler/cooled on the outside edge get the larger main jets

Easy to check before you delve into everything else

 

How good

 

Hi all,

I am finally taking my bike in for a reregistration check this Friday… have been putting it off for so long waiting for those carbs, now she’s back together I’m hoping it all goes smoothly and passes.
Here in NZ because it’s previously been vinned and registered it should be fairly straight forward - much like a warrant of fitness check but a lot more thorough.

Will let you guys know!

 

@Frankster @ruckusman thanks I’ve just noticed your replies sorry didn’t get the notification.

I’ve had it running for an hour or so and seems to be revving up just perfect atm, yet to change the other 2 plugs but will do that this weekend. Cheers

 

So I’ve noticed spark jumping from the #1 cylinder lead jumping to the valve cover. Is that a clear sign I need new leads?

 

Well that shouldn't happen. Check the quality of the insulation on your leads. Also check your plug. If they are resistor plugs, maybe the resistor has gone open circuit. Maybe if there are resistors in the plug caps they may also have gone open.
You could also just move the plug lead away from the cam cover but that will not solve the problem.

 

Yeah I've been hearing a clear 'click' from which I know see is the spark jumping from the spark plug cap right about where it reads "NGK" as in your photo above and directly across onto the inner face of the valve cover. I noticed while running it in the dark but can see it clear as day in the light too.

I was wondering about the leads, I bought a set from the local super cheat but I suppose they wont be suitable. I'll read through that link thank you!

 

I got some high quality replacement lead wire, proper suitable stuff for bikes from the local bike mechanic

Getting the clips off of the coils is a real trick, as others have noted, not breaking them is the knack - it can be done

 

So changed the #1 + 2 plugs. Noticed the lead caps are 5ohm. Anyway put the caps back on and the #1 lead fell out of the coil…with two cable ties which I assume were there to hold it in place.
So I have managed to buy a second hand pair of coils with leads etc - will try them out on the weekend and fingers crossed she runs abit better.

 

So I’ve replaced the coils - no more issues there. However, I’ve run the bike with the air filter off and noticed the #2 cylinder carb ‘slider’ isn’t moving at all when I rev it. I’d say that’s my problem - any ideas what’s happened there and can I fix it without taking the carbs off?
Here’s a photo:

 

Just spoke with the gentleman who rebuilt them and he says the sliders should only be working with the tuned air box on/filter box. Have put it back on and is running a lot better, but, there’s still that hesitation under full throttle which I can’t help but think is that #2 throttle slider.

 

Yup whipped the carbs off and took them to him for an inspection and sure enough it was the pinched diaphragm. Am absolutely itching to get them back on and test her out. Fingers crossed this will be the golden nugget.

 

To be fair though without the air box on it won’t rev properly, perhaps on another bike he’s experienced it.
Anyway, so pleased to say it’s finally running like a dream, Revs hard all the way to redline. I’d forgotten how much fun these bikes are! For a little pocket rocket they really excite the nerves.
There’s a very slight hesitation down low on part throttle, very slight though so nothing I’ll worry about.
Thank you all for the great advice. Next step will be sorting the warped rear disc - I had to replace it for compliance and the second hand one I put on and passed declaration on is warped. They required a minimum thickness of 4.6mm from memory.