ZZR400 mystery bogging

**imthatguy** · 12th June 2015, 16:17

Hey Guys,

some time ago I posted about my ZZR400 (1992) which was having some issues bogging when under load.

Since then I have bought another toy so the project has been somewhat put on hold but Im still having issues with it.

So far I have:

- check, cleaned and ultimately replaced carbs with a set from a runner
- checked, cleaned air filter, tried without
- checked ht leads and replaced with no change
- checked charging system
- drained fuel countless times, cleaned fuel tank, tried without fuel tank
- checked, cleaned ultimately changed plugs
- checked, charged battery
- checked for bad earth etc, resistance checked as much as I could, no issue apart from a routinely blowing headlamp fuse
- checked coils

Im really running out of things to try, bogging wouldn't be caused by an engine issue would it, I mean even really low compression would just manifest itself as lack of power, it wouldn't bog..

Since the issue originally started on a trip up to Auckland its also become progressively harder to start and idles worse and worse.

Does anyone have any other ideas? Im thinking next steps could be CDI and pickup, I understand coil issues normally show up only when the bike warms up?

Cheers guys,
A

**caseye** · 12th June 2015, 16:49

There are others here far more able to speak with knowledge and experience but I would be looking for air leaks to and or from your carbs, check that your gas tank cap is venting.Apart from that, keep trying.

**imthatguy** · 12th June 2015, 16:55

Originally Posted by caseye

There are others here far more able to speak with knowledge and experience but I would be looking for air leaks to and or from your carbs, check that your gas tank cap is venting.Apart from that, keep trying.

Thanks Mate, have thoroughly checked all carbs and surrounding areas for leaks.
Its definitely not an issue with gas tank as I have tried without it to the same effect.

**Akzle** · 13th June 2015, 19:53

adjust your valves oi

**Akzle** · 13th June 2015, 19:54

also. Check the carb boots again. With crc.

**nzspokes** · 13th June 2015, 20:21

Bet your carbs have worn needle guides. My old kwaka did exactly that. $30 of guides sorted it.

**Akzle** · 14th June 2015, 11:06

and check your cct, afore your shit gets 'splodey.

**imthatguy** · 14th June 2015, 20:06

Originally Posted by nzspokes

Bet your carbs have worn needle guides. My old kwaka did exactly that. $30 of guides sorted it.

Just to reiterate, same symptoms with two sets of carbs, the chance of them both being warn seems slim no?

**imthatguy** · 14th June 2015, 20:09

Originally Posted by Akzle

and check your cct, afore your shit gets 'splodey.

Ok Ill try checking valve timing next. I wouldn't have though it would cause the engine to bog but will check it out anyway. I guess that would be consistent with it getting progressively worse..

There is definitely no air leaks anywhere I have checked with crc a few times.

I will do though I would expect to hear it rattle if it was loose no?

Thanks for your help.

**nzspokes** · 14th June 2015, 20:14

Originally Posted by imthatguy

Just to reiterate, same symptoms with two sets of carbs, the chance of them both being warn seems slim no?

Slim? Not at all. Most carbs will do it. Did you check them before you fitted the second set of carbs or just hoping they are ok?

**imthatguy** · 14th June 2015, 20:28

Originally Posted by nzspokes

Slim? Not at all. Most carbs will do it. Did you check them before you fitted the second set of carbs or just hoping they are ok?

Haha to be honest I just hopped they were ok. If was a $250 set of carbs of a newer and lower millage bike (apparently), I hoped they would be better lol.

What would I look for?

**ducatilover** · 14th June 2015, 20:32

Originally Posted by imthatguy

Just to reiterate, same symptoms with two sets of carbs, the chance of them both being warn seems slim no?

CVK Keihins of the era are known for it. Emulsion tubes made of Camembert

Have you sync'd the new carbs? Or the old ones?
What revs is it bogging at?

Sell it to me if it's a K model

**Akzle** · 14th June 2015, 21:51

did i say timing? I meant clearances.

Ovals where circles should be, is what youre looking for in your carbattery.

**imthatguy** · 14th June 2015, 23:50

Originally Posted by ducatilover

CVK Keihins of the era are known for it. Emulsion tubes made of Camembert

Have you sync'd the new carbs? Or the old ones?
What revs is it bogging at?

Sell it to me if it's a K model

Haha yes I remember you mentioning it on my last post ducatilover,

Eye synced them both, don't have gauges for proper sync but was going to take it in once it was working ~70% or so.

Its bogging literally everywhere but worse at midrange I guess. If I put my hand over the airbox opening it revs fine.

Haha whats your offer? just on 40k, new blood red faring kit, purrs like a cat when running correctly, been all over the NI on it with a pillion on the back!