Kawasaki ZX7r 2001 Lumpy and rough. Help/ideas please.

[spannermonkey...]

Hi all brain teaser.

Day 35 in the garage post rebuild.

I carried out a piston ring change as it sounded rough and carb balancing couldn't sort it and only two valves were tight. So I was low on compression after a wet check. I checked the bores as per the book and honed with new rings, head is flat with valves lapped in with correct clearance and timing. All new parts used if near tolerances.

No fancy mods all standard except for a motad headers.

First start after a rebuild and it ran really sweet. It ran for 5 minutes, while I was purging air from the water system. Then when I restarted it ran like a twin or triple

So I checked and cleaned the carbs again, fuel level spot on (I've done both tests), pilot air screw clean and set to 1 3/4 out (UK) diaphragms good as was everything else.

Also tried timing 180 over but kind of pointless when it has a wasted spark.


Fuel pump was iffy and was bleeding internally so no pressure at the carb so changed that for a Kawasaki one as fed up with pattern part rubbish.
Carbs balanced or close as cant run it long enough to get a good value but really close on the gauges.

I have resistance checked the CDI, pump relay, pick up all good as per the book.

I had DYNA coils and what rubbish lasted less than a year. Supposed to be 3 ohm but now measure 5 ohms with secondary windings around 14000. So I brought a pair off fleabay at 20 each, just worth a punt, they put out 2.8 ohms and 18000 ohms. Meaning the amp of the spark is bigger than so called performance parts so don't waste your money on dyna coils.

New leads and caps.

So now the engine starts and runs even idles but sounds like a triple or twin, header pipes are all hot at same temp.

It coughs out of the carbs intermittently with air box fitted with standard air filter. Lean? so played with pilot air screw no change, check valves again and within tolerance and timing is good.

So I popped the new plugs out, one was slightly sooty but dry, the other three were wet, top of pistons are wet also.

Oil/Fuel? possibly.

Can the float needles cause this, leaking past the seat, could it be the rings? I've honed them in but with hardly any run time they are still new so compression would be low still - 7.3-8 bar across all 4.

could the head of lifted after first run?

What do you all think?

I have con/volt checked wiring, switches, ran it in the dark looking for sparks from the ignition system.

I'm aware of fuel passing the rings and filling the sump. it will be changed once it behaves.

By book I mean Kawasaki service manual and Haynes.

any help would be great.

[spannermonkey...]

Cleaned the carbs and replaced the needle and seat, float adjusted to 13mm/ 5mm below line.

Still runs like a triple. Number 2 cylinder header pipe colder than the others a lot colder.

Oil present on piston crowns doesn't clear.

Rev up to 10K and still sounds lumpy. (once warm)

Thinking of getting a compressor to blow the carbs out.

If it runs better I will buy new jets. But if it ran up to 10k sounding lumpy then it cant be the 2 lower circuits in the carb.

if it's rubbish, check cylinder head for tightness when cold.

Then I will strip it down. Replace the rings, hone again keeping within limits and ring gaps checked.

Check the head over and replace valve stem oil seals and go from there.

Cant be anything else or have I missed something obvious.

But any other ideas would be great before I rip into again.

[misscrabstick]

has it got that system that shoves air into the exhaust via some reed valves in the head? something gone wrong with it and the engines sucking in exhaust gas? just an idea.

[spannermonkey...]

Yes I have all the junk on the head and I'll have a look, as I've seen something in the service manual to test them I think. Maybe as a quick test just remove them and block off to see it works.

Hopefully it's that simple. I will report back tomorrow.

[spannermonkey...]

I have run it again this morning a still no fun on the no2, it runs but the headers are cooler than the other 3.

I also removed all the suction valve stuff and checked the reeds and still didn't run right. I have the carbs off and stripped ready for blowing through. Upon looking in the cylinders and with a cotton bud I have taken a sample of fuel/oil off the piston crowns. It smelt like fuel but kind of oily, so I had a look down the inlet track with the valve open on the no1 cylinder I could see a cloudy substance on the piston crown, cotton bud again and it's oily like - cloudy makes me think oil and fuel mix. Didn't find this on any other piston. So plan is blow through carbs and run it and check balancing. If that fails. Strip it down, check valve clearances and head torque then fit (maybe new rings) and then lap in the valves again not going past the limits with a very fine grit paste and rebuild.
maybe the oil is playing havoc with the bang and when you smell the oil inside the filler cap it doesn't smell to good.
I did a compression test cold (I know the engine has to be warm but for investigating I gave it a go) they range from 7.4 to 8 dry and 10-12 wet. So a re hone and re lap is in order. I understand dry being low but wet not making minimum is a little pants.
I don't have a leak down tester. I did a static leak test with the head upside down with oil in the crowns and didn't leak but no pressure except atmosphere.

Time to drop the engine out and have a look around.

What I find a pain in the bottom is that I'm self taught and that it is very difficult to find people to ask questions in the UK that and pattern parts.

[misscrabstick]

Oil is too thick to use as a valve leak check, we use brake cleaner at work when we have to check a head and valves after a timing belt failure, that said though we have seen slightly bent valves seal perfectly with this test because the spring can pull the head straight on the stem under pressure, it's when you try and lap them in you see the issue as you can't get a nice even matt grey stripe on the seat all way round the valve.

When your doing a compression test don't get too hung up on the actual max values, gauges can vary hugely in accuracy, ideally all cylinders want to be within 10 to 15% of the highest one.

[spannermonkey...]

I think I have it, I have deglazed with a too course hone, keeping the oil high in the cylinders and the rings not clearing. I used a 180 grit and I later found out a 220 would be better. too course and it takes an age for the rings to seal meaning high oil consumption and to little and it the long run accelerated ring wear.

I'm going to sort out the bores and polish the valves seats to get a better seal. My valves are straight but will check again.

I will find a thinner medium for compression check, I was just following the dreaded Haynes manual.

I know about gauges, I have 3 tyre pressure gauges that give a broad spectrum of psi/bar on the same tyre.

Thank you for the comp test info. As the manual is rather grey in that area.

What grit lapping paste do you use for valve grinding as is polishing a valve seat a good idea, being two faces smooth against each other.

[evoboy]

Are all the pipes for the carbs in good condition?

The zx7 uses pressurised float bowls. When mine had issues like this ( one of many I might add) it was due to a split vac pipe.
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Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

[misscrabstick]

Valve paste usually comes as fine and coarse, some say if you have to use the coarse to get a good seat then you should consider a proper seat recut on the head and valves by a machine shop, your looking for a nice matt grey band on both the head and valve after grinding in, remember to clean up thoroughly, you don't want paste in your engine.

[spannermonkey...]

Carb fuel pipes are new, the vacuum pipes are good and no visible splits. I will replace the thin vacuum pipes just to be sure.

I even ran it with all the emission stuff removed and no joy exactly the same.

Just doesn't explain the oil on the pistons.

[mentalboy]

[spannermonkey...]

Well with the high oil content in the cylinder I don't want to hydraulic anything, so getting it hot to do a compression test is a little far off at the moment. I will do this once it's oil tight.

[spannermonkey...]

Hi all time for any update.

Engine is apart and what I had noticed was fluid in the intakes was in fact cracks in the inlet ports causing the coolant issue.

Second hand later and it looks good when stripped, but that's gone for pressure testing, skimming and a good bath.
New head £1800 from Kawasaki - still after 13 years. So for the cost of that I could do the job many times over or just get another bike.

I looked at the barrels and the deglaze job I had done wasn't enough and was quickly polished off and the rings had also lost their edge.
So my hone was to course as expected resulting in oil staying high and fuel passing the rings.

So lesson learnt really, don't bother honing at home without a bottle type hone. get your head pressure checked.

In future I'll stick with 2 strokes and the tuning of. But once done should be sweet as.

Will report back in a week with my new parts from the machine shop.
and a cost just to give an idea to anybody still reading this far down.
Head cost £25 to skim. Not sure on the rest.
TTFN

[Zx7rSWFC]

Have you checked all fuel hoses (condition/kink) from the fuel tap running to your fuel filter, along with the foam insulation surrounding the hose? also check the fuel hose running to the fuel pump.

Also make sure the breather pipe is okay/connected/not clogged..

Good luck with it.

[spannermonkey...]

Hello all if your still reading this far down.

I have had the head pressure checked, seats and valves cuts and the barrels honed along with all surfaces being checked for flatness.

Head rebuilt and static leak check done on the bench, didn't loose a drop of thin oil overnight.

ring clearance is awesome as it the piston. Valves are good also. swapped a few around from the old head to the new to get the best of both (all valve parts grouped together and cut together) Carried out a cam journal clearance check and that miles in. Using the old cams as they measure better and it matches the cam chain.

Been told by Kawasaki to run it on thin mineral oil and to keep the revs below 4000rpm for the first few hundred miles. Then once it frees up, increase the rev range.

Today I will put the head on and start the shim thing. starting from scratch but I have a bucket load of shims to play with.
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Current machines - Aprilia RS250. Kawasaki H1A 500. Past machines - Kawasaki ZX7r P6, Yamaha RD250E (the one that got away), BSA Racing bantam (revs over 10'000 sweet as), Yamaha RXS100, Suzuki GP100, Suzuki GS500K2 - best all year machine ever - come rain, sleet and snow just epic.

[spannermonkey...]

After sorting the head and cylinders.

Bike rebuilt and it ran rough, all headers were warm. The info I was given for the pilot air screw was rubbish. Kawasaki say 1.75 turns out and Haynes is rubbish. I statically set the carbs.

Still ran rubbish, one header pipe was slightly cooler hinting it was rich. so I gave up and got the carbs balanced locally. I have the kit but not the experience with a bike that far out.

I gave in for the first time in 15 years and went to a bike shop. I got the mechanic to balance my carbs and set the pilot air screw. He had an all bike type bible. My pilot air screw setting was miles off. should be 2.25 out.

Picked it up and it ran good but had an air leak. Fixed the air leak, airbox to carb issue and it's still tight after 100 miles. Can't wait till it's run in. Engine feels strong and it's usable from 2000 rpm. I've only got to 4k so far but it's promising.
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Current machines - Aprilia RS250. Kawasaki H1A 500. Past machines - Kawasaki ZX7r P6, Yamaha RD250E (the one that got away), BSA Racing bantam (revs over 10'000 sweet as), Yamaha RXS100, Suzuki GP100, Suzuki GS500K2 - best all year machine ever - come rain, sleet and snow just epic.