Kawasaki ER5 1999 running issues

[Malvern]

I bought an ER5 (1999) which had been someone’s project and I’ve been trying to fix its issues! I’ve got to the point where all the electrical gremlins and general maintenance issues are resolved but have an issue when running:

The bike starts and revs absolutely fine, when riding it bogs at about 3500rpm in all gears. The bike has an aftermarket exhaust and filters fitted and I’m not sure if the carbs have been adjusted to suit. Does anyone know a good method to check if this is the issue and whether the mixture screws need messing with of new main jets? Or have a suggestion what else it could be? The carbs themselves are very clean and functioning well.

[jeffyjeff]

[Robby]

Aftermarket air filters - is that a K&N filter in the original airbox, or is it running pod filters?

If you're running pod filters, get an airbox. That particular engine in its various incarnations is known to rely heavily on the airbox to run right.

The for carb setup, start off with the factory settings from the manual for both jet sizes, float height, needle position and mixture screw.

Then you have a baseline to work from. I would generally open the mixture screw out another half turn on a bike of that vintage when it was fashionable to have a lean idle, but after 20-30 years of wear it just produces a weak, stumbling idle. Then if it is still cocking around at 3500rpm I would raise the needles one notch.

Main jet only becomes a limiting factor at close to full engine power. For everyday riding you tune on the needle.

[Malvern]

Thanks for the replies guys.

It doesn’t go above 3500-4000 rpm in all gears, absolutely fine up to that point. When it’s on the stand it’ll Rev up to screaming no problem, it’s just when I’m actually on it and riding.

It’s aftermarket pods that are on it along with an aftermarket exhaust. There have been some mods done to the bike which will mean refitting an air box is not possible since there’s no room for it any more.

I stripped and cleaned the carbs, there were no obvious issues.

I’ll have a (logical) play with the air/fuel screw. The issue being that there is only an issue when riding and not on the stand do adjustment and testing is going to be slow! I also don’t have the special tool for reaching the screws so I’ll have to figure something out!

[jeffyjeff]

[stinkwheel]

It needs an airbox. No danger it'll run properly without one and that huge flatspot is exactly what you get on those with no airbox.

If you thrash the living tits off it you can probably get it onto the main jet (about 7-8,000 rpm) and it'll pull through the flatspot but then you're stuck riding it at wide open throttle everywhere making it unrideable.

There are a couple of accessory jets that take care of fuelling at the rev range in question (brass jets facing backwards towards the air filter round the edge of the carb choke). make sure these are clear by blowing through them with compressed air/carb cleaner spray.

Cheap, easy fix. £14.. There are cheaper but this one has the rubbers/intake trumpets and clamps on too.
https://www.ebay.co.uk/itm/Kawasaki-ER5-ER-5-OE-Air-box/363016352548?hash=item548575f324:g:XLAAAOSwbw1Z-JCR

Get a new air filter at the same time.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Robby]

Also worth mentioning that the mixture screw only affects the mixture at idle and very low engine power. Your problem will not get fixed with the mixture screw. You'll be removing the carbs a lot to fiddle with them.

[Malvern]

Thanks guys, I’ve fitted an air box back in and it now runs fine....next issue is the coolant reservoir, which the previous owner re-sited since they removed the air box and modified the tail. I now can’t find a home for it!

[Malvern]

This is where it was!