MC22 flat spot

[Driftmonkey]

Been riding my MC22 for a bit now and there is a flat spot in the rev range that has been bugging me. It's from about 12~15k rpm. Wouldn't have a clue whats causing it. Or how to fix it.

Any geniuses keen on chiming in and making sense of my utterly useless description of this problem?

TL;DR

Flatspot from around 12k to 15k rpm. How to fix it.

[Akzle]

TL;DR

Flatspot from around 12k to 15k rpm. How to fix it.

youre a beautiful man.
Has it got some vvt shit?
What is ignition?
Them little bikes gay up like that sometimes...

[Driftmonkey]

Hahaha, 1990 MC22 with 61k kms. Not a good mixture for carbs I think. I know it could be a billion different things. I'm wondering if I can start with any intank additives that might dissolve any gunk or shite that's clogged up somewhere in the carbs? Not really keen on pulling them out and doing a full clean on them as I can live with it as its only minor (rather be out riding the thing).

[Akzle]

Hahaha, 1990 MC22 with 61k kms. Not a good mixture for carbs I think. I know it could be a billion different things. I'm wondering if I can start with any intank additives that might dissolve any gunk or shite that's clogged up somewhere in the carbs? Not really keen on pulling them out and doing a full clean on them as I can live with it as its only minor (rather be out riding the thing).

you, fuken, cunt.

drain your bowls an' run half a litre of meths through your next tank.

But that aint gona fix your shit.

[Driftmonkey]

you, fuken, beauty.

drain your bowls an' run half a litre of meths through your next tank.

But that aint gona fix your shit.

Sweet as, will give that a crack and complain on here more when it doesn't work.



However, if it does work. You're a legend.

[FJRider]

Flatspot from around 12k to 15k rpm. How to fix it.

Buy an NC30 ... MC22's are for monkeys ...



Oh wait ..

[Driftmonkey]

Buy an NC30 ... MC22's are for monkeys ...



Oh wait ..

My username doesn't seem too popular on this particular forum.

Bikes can drift too.... can't they?

[ducatilover]

Meths won't help. Unless you want to lose weight.
Start by doing the normal shit, decent petrol, check the plugs. Then start getting in to the carbs.
Has it got a good standard air filter and standard exhaust?

[Driftmonkey]

Meths won't help. Unless you want to lose weight.
Start by doing the normal shit, decent petrol, check the plugs. Then start getting in to the carbs.
Has it got a good standard air filter and standard exhaust?

Plugs will be first on list to check, not sure about air filter, will investigate that also. Exhaust..Looks stock + sounds stock. 299344

[swbarnett]

Does the flat spot always happen at the same rev range irrespective of what gear you're in? Or is it more that it happens at roughly the same point on the throttle?

[Driftmonkey]

Happens through every gear at full throttle, not really noticable with less throttle. I just took it for a ride before and it feels much better. Might have been a bad batch of petrol?

[swbarnett]

Happens through every gear at full throttle, not really noticable with less throttle. I just took it for a ride before and it feels much better. Might have been a bad batch of petrol?
Certainly not what I was thinking then. My problem was at about 1/4 to 1/2 throttle and I had to replace some parts in the carbs.

[FJRider]

Happens through every gear at full throttle, not really noticable with less throttle.

Here's a thought ... use less throttle.

The bike may last longer ... and so may YOU ...

[ducatilover]

Here's a thought ... use less throttle.

The bike may last longer ... and so may YOU ...

:facepalm: Come on FJ, you're better than that?

[speeding_ant]

Here's a thought ... use less throttle.

The bike may last longer ... and so may YOU ...

But.. but.. 19,000 rpm is the only way to get anywhere on these things... probably has 1/10th the torque as your bike :rolleyes:

[The Pastor]

Take the carbs apart and clean them would be the 1st step.

also check air filter, fuel filter (its above the fuel tap - remove any inline filters - they are not stock) and spark plugs

Then balance the carbs (also check valve clearance before balance, but mc22's tend not to need adjustment, but check to rule it out)

[The Pastor]

http://cbr250.com/forums/maintenance/218-cleaning-carbs.html

[The Pastor]

http://litetek.co/Carb_Kit_Honda_CBR250RR_MC22.html

[speeding_ant]

Take the carbs apart and clean them would be the 1st step.

also check air filter, fuel filter (its above the fuel tap - remove any inline filters - they are not stock) and spark plugs

Then balance the carbs (also check valve clearance before balance, but mc22's tend not to need adjustment, but check to rule it out)

Yeah, these are good things to check. If your carbs have never been off before, just be careful with the rubber boots and seals on the intake and air box. They tend to crack easily. While you have the carbs off, check throttle cables for rust too, mine were almost rusted through. Cleaning the carbs is an easy job. Don't take the diaphragms out until you've inspected the bowls, as if the bowls aren't varnished and ming, it's probably not worth the risk of damaging the diaphragms as they're quite fragile. You can check to see if the diaphragms are working by simply hearing the suction when you push on the slide. Use an air compressor to clean the jets too.

That's all I got. Warning, I know bugger all too.

[matrox02]

Yeah, these are good things to check. If your carbs have never been off before, just be careful with the rubber boots and seals on the intake and air box. They tend to crack easily. While you have the carbs off, check throttle cables for rust too, mine were almost rusted through. Cleaning the carbs is an easy job. Don't take the diaphragms out until you've inspected the bowls, as if the bowls aren't varnished and ming, it's probably not worth the risk of damaging the diaphragms as they're quite fragile. You can check to see if the diaphragms are working by simply hearing the suction when you push on the slide. Use an air compressor to clean the jets too.

That's all I got. Warning, I know bugger all too.


I had all sorts of problems with my mc17, look on ebay and get some new carburetor boots and replace those first, they were the single best thing i had ever done for that bike, never had a problem after that

[Icemaestro]

that exhaust doesn't look stock to me. which would explain something - maybe needs jetting looked at, esp given the rev range you are having problems in - that high up should be main jets I would have thought, that and/or air filter system or fueling.