Topping out at 110mph

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cargo
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Re: Topping out at 110mph

Post by cargo »

And before Cargo says "so what were you hanging about for?" I realised my hopes of becoming a road racing superstar were slim as some smartarse on a Gixxer shot past my earhole like I was on a trip down the shops vsad

Been there and got the t shirt.

Last right hander at the end of the Mountain Mile is flat out but it takes a brave man to do it. I was on the 400 nice tight line about 3 feet off the wall on the inside and Davy Morgan came past on the inside of me flat full stick on a proper race 250..............scared the living 5h1t out of me I thought I felt him touch me.

After the race he came and apoligised
He was dicing for the lead.....................and needed to get past me.

Top bloke by the way
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banner001
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Re: Topping out at 110mph

Post by banner001 »

compression test, cold engine, no oil down bores:-

#1-125psi
#2-118psi
#3-122psi
#4-123psi

range should be 99-156psi, but i did it cold so might need to re-do with a hot engine. seems that there is no one individual cylinder that has low compression, but i suppose they could be closer to the 156psi maximum....? might have to look at getting a leak-down test done as well.
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Tirpitz
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Re: Topping out at 110mph

Post by Tirpitz »

banner001 wrote:compression test, cold engine, no oil down bores:-

#1-125psi
#2-118psi
#3-122psi
#4-123psi

range should be 99-156psi, but i did it cold so might need to re-do with a hot engine. seems that there is no one individual cylinder that has low compression, but i suppose they could be closer to the 156psi maximum....? might have to look at getting a leak-down test done as well.
You have to do it with a hot engine. The rings don't seal properly when the engine is cold / dry. It's also possible that if you have a leak caused when the engine is hot you will be missing this on a cold test.
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banner001
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Re: Topping out at 110mph

Post by banner001 »

ok, i did notice that it said to do it hot, but i have also seen posts where people say test cold, then hot, then hot with oil in bores.

so i should expect the numbers to increase when hot (as they are sealing better), unless i have a leak in the system somewhere?
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Re: Topping out at 110mph

Post by Tirpitz »

banner001 wrote:so i should expect the numbers to increase when hot (as they are sealing better), unless i have a leak in the system somewhere?
Correct.
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banner001
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Re: Topping out at 110mph

Post by banner001 »

ok ill get ready for some burnt fingers :D

ill also try to procure a leak-down tester. my mate has a fully stocked garage (think 3 bike lifts, 12 bikes, a beer-hall with 7 seats one of which is a wheelchair, all manner of engine tools, cnc water-jet facility, metal lathes...the whole lot!) but no leak-down tester, ill go back, do the compression test with a warm engine and do a leak down test afterwards (i can buy the tester, but i dont want to also have to buy an air compressor).
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JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
cargo
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Re: Topping out at 110mph

Post by cargo »

I very much doubt that a carb issue wil allow a bike to rev completely normally then suddenly at 110mph start causing problems.


The problem you discribe................reving normally then a sudden problem at 110mph very much DOES sound like a restriction issue.


In fact your description sounds like a restricted ZXR400 that has the full restriction still in place.


Also in your description you demonstate that you do NOT understand how the restriction in ZXR400s works.

Restricted ZXR400s.............rev completely normally to the normal red line in everyway but once 110 mph (no matter what gear your in) is achieved it will NOT go any faster.
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Re: Topping out at 110mph

Post by CaNsA »

Cleaned up this thread.
Joe, you have your own thread, be patient, let the lads fix 1 problem at a time.
Stop hijacking this thread!


@banner.....

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Tirpitz
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Re: Topping out at 110mph

Post by Tirpitz »

cargo wrote:I very much doubt that a carb issue wil allow a bike to rev completely normally then suddenly at 110mph start causing problems.


The problem you discribe................reving normally then a sudden problem at 110mph very much DOES sound like a restriction issue.


In fact your description sounds like a restricted ZXR400 that has the full restriction still in place.


Also in your description you demonstate that you do NOT understand how the restriction in ZXR400s works.

Restricted ZXR400s.............rev completely normally to the normal red line in everyway but once 110 mph (no matter what gear your in) is achieved it will NOT go any faster.
So if he's not got a pink restriction feed from the clocks to the CDI do we then assume that whoever has restricted it has used another colour wire?

Banner - why don't you look at your CDI in conjunction with the L model wiring diagram and the service manual supplement. This shows you what wires should go into the CDI and their colours. If you have an extra wire to these then that would seem to be the restriction wire. Presumably the restrictor feed goes to the otherwise unused pin on the 6-pin block on the CDI? If you have 6 wires going to that block then you've got one too many.

If it is this a UK M CDI isn't going to set you back much, plenty on Ebay.
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Re: Topping out at 110mph

Post by R P Corse »

Tirpitz that pink wire feed... That other wise known as the "magic box"

... Like this?
ImageUploadedByTapatalk1344612778.239267.jpg
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banner001
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Re: Topping out at 110mph

Post by banner001 »

Tirpitz wrote:
cargo wrote:I very much doubt that a carb issue wil allow a bike to rev completely normally then suddenly at 110mph start causing problems.


The problem you discribe................reving normally then a sudden problem at 110mph very much DOES sound like a restriction issue.


In fact your description sounds like a restricted ZXR400 that has the full restriction still in place.


Also in your description you demonstate that you do NOT understand how the restriction in ZXR400s works.

Restricted ZXR400s.............rev completely normally to the normal red line in everyway but once 110 mph (no matter what gear your in) is achieved it will NOT go any faster.
So if he's not got a pink restriction feed from the clocks to the CDI do we then assume that whoever has restricted it has used another colour wire?

Banner - why don't you look at your CDI in conjunction with the L model wiring diagram and the service manual supplement. This shows you what wires should go into the CDI and their colours. If you have an extra wire to these then that would seem to be the restriction wire. Presumably the restrictor feed goes to the otherwise unused pin on the 6-pin block on the CDI? If you have 6 wires going to that block then you've got one too many.

If it is this a UK M CDI isn't going to set you back much, plenty on Ebay.
defo dont have a 6th wire to the unused middle connector...all others are color coded as in the manual so i assume they are stock.

have found 3 things that dont add up:-
1. i am having this problem with the misfire
2. having taken my current carb apart the bottom of the bellmouths are warped on #2, #3 and #4 and are not sealing properly, they also look to be obstructing airflow a bit.
3. some CDI resistances are wrong

i have posted a question in the electrics section about a few odd resistances in my CDI, if someone has an L or M-spec CDI, can you have a look at a quick resistance check for me, its only under the rider seat...thanks
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banner001
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Re: Topping out at 110mph

Post by banner001 »

ok, am going with a combination now of:
1. jetting problem (definitely)
2. crap HT leads (cant harm)
3. might do with new CDI (will see)
4. coils (dont think so)

managed to get 125.2mph the other day, cant remember what clock was saying, but it was pulling 13600rpm in 5th gear, have done some carb work as they were setup bad, getting better now, but its really lean at high revs, so new mains 98's or 100's will be here come payday, as will new HT leads, ill test the jets out and see what works best.

cdi seems ok, but i would like to test it agains a knows good one.

coils are ok-ish, primary resistance is a tad high at 3.8 ohms, but secondary's are fine at ~14.4k ohm...so i dont think they area problem.

will see what happens when the jets get here, but i am almost sure its jetting/bad contacts from HT leads...they are the 18-year old originals, and are corroded/breaking metal off at the ends...
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JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Re: Topping out at 110mph

Post by marklwhittaker »

just a thought
what size sprockets you got on?
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banner001
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Re: Topping out at 110mph

Post by banner001 »

its stock sizes, 15 and 45 teeth
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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