Kawasaki ER-5 1998 Problems

[RichuK]

Hello! So I have this Kawasaki ER-5 which neither me or the workshop is able to get to run properly, everything is stock with it. It has original air filter box and everything. Anyways the problem is that it does not want to cruise at steady speeds and it doesn't like WOT. So pretty much it is fine with like 0-20% of throttle, it coughs and hesitates to move at 20-80% of throttle and hauls ass at about 80-90% of throttle, over 90-95% it starts hopping and bogging out, making it not a very enjoyable bike to ride. It has had valves clearenced, carb cleaned, rebuilt and so on. Don't really wanna invest much more money into it since I've spent about 1000 bucks trying to get it to work properly... Is there any way this bike is gonna run properly or should I just sell it? I'm kind of tired of the problems.. Last time workshop tryed raising the needle with a couple of spacers, which made it nice and rideable up to half throttle and max out at 6000rpms(it also cruised great then but max speed was 120kmh), since then spacers were removed and the bike can get up to 8000rpms 150kmh but does not like to cruise at much lower speeds

[Robby]

Well it sounds like fuelling.

It can rev up high enough, so it's making sparks, probably at the right time. It's had the valve clearances checked, which rules out an obvious place where you can lose compression. And fiddling with the fuelling made it a bit better in one way, but worse in another.

Fuelling on carbed bikes is affected by several factors - jet sizing, needle position, float height. Mixture screw is also there, but only has any noticeable affect at idle.

Then there are the external factors. Fuel flow - is the fuel tap clogged. Air flow - is the air filter any good. On these engines in particular, does the air filter have a big hole in the middle of it.

The proper diagnostic path is to check the external factors first - so make sure you have good fuel flow from the tank and fit a new air filter.
Then get a workshop manual and set the carbs to whatever it says in there. This is likely to involve a couple of rebuild kits to get the right size jets, and new needles won't hurt.
Then if it still doesn't work, you can start fiddling with jetting. The easiest way to do this is on a dyno, where you can get data to tell you how the bike is behaving.

It should work in standard form, but it's an old ER5 so who knows what has been done to it over the years. Aftermarket (loud/free flowing) air filters and exhausts will affect this. In the unlikely event that it has had serious tuning work on the engine, this will affect it more.

It's all a fiddly painful process, quite expensive if you go down the dyno route, and all you get at the end of it is an ER5 that runs well. Barely worth the effort.

[stinkwheel]

Re-check the power-jets on the carb. Normal low running then a huge upper midrange dead spot you can pull through and rev-out is classic of blocked power jets and normal routine carb cleaning doesn't necessarily get into them. Had this on a GPZ, it would run fine up to about 6k and then (literally) nothing until 8k whereon it took off like a scalded cat. So it was either plodding or thrashing. It had sucked bits of disintegrating filter foam into the power jets, they had to be hooked out with a fine wire then blown through. Fun times.

Done the plugs? If the cylinder head drain holes get blocked, water can build up in there and leave the plug recess/plug/plug cap a mass of corrosion and muck. Can even rot out the threads in the head if it gets too bad.

Make sure the coil earths between the mounting bracket and frame are in good order, these also tend to get rusty underneath.
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“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.

[MCN]

Coils can break down over time.
They may provide power at low rpm but breakdown when a big fat spark it needed in quick succession.

They can be tested individually.
But perhaps replace with proven good used would be simpler.

And the carb/fuel thing. More complex and finnagaly.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.