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Carb fuelling problem
borg230rover - 29/7/12 at 11:47 PM

Mac R1 Turbo rich

Hi can anyone help me.

I have completed the build of my carb'd yamaha R1 Turbo Mac about 1500miles ago, it drives very nice and you wouldn't know of any underlaying problems that it had as I didn't until last week when I took it in for a rolling road tune.

Let me explain,

I drove about 40 miles to PDQ in Slough to get a roading road tune, the guy hooked it up to the rollers and gave it 3 good runs, after which he said to me the car is running dog rich so bad infact that the wideband sensor could not keep track of it and as soon as the car reaches 3000rpm the richness line goes way off the scale.

No problem he thought and changed the main jets to a more suitable size, checked the needle positions, fiddled with the mixture screws a little and then run it up again. This time the car was mega lean.

From that we though right we are on to something here the first jets 1.44 dog rich, the second ones we tried were way to lean 1.20 so lets try something in the middle so the changed the main jets to 1.32 smack bang in the middle.

Guess what it would barely run at all would rev a couple of times up to a max of about 5000rpm then cut out, would always start again though no probs.

We couldn't understand what the hell was happening.

We then decided to adjust the boost pressure on the turbo from 7psi upto 14psi (.5bar to 1bar) and every where in between but it made no difference (this engine has turbo pistons/rods/head studs/gasket etc) before anybody asks.

In the end we carried out 9 runs all of which were dog rich.

The rolling road guy reckons that the car has something else effecting the fueling a few ideas that he came up with was that the waste gate was sticking open and the car wasn't boosting properly, or the fuel pressure regulator was not working correctly. I personally thought that it maybe the fuel pressure regulator to fault but as of yet can't prove or disprove that, I have put a fuel pressure gauge in the fuel line and it does tick over at 3psi of fuel pressure which Jack Frost from Holeshot Racing recommends is the correct pressure, the fuel pressure does appear to rise quicker than the boost but they do end up at roughly the same pressure which will be causing a slight problem but not to the extreme that would cause such richness (i dont think)

I am about to change the fuel feed and return lines because at present I do believe that the feed line is a larger diameter than the return (feed 10mm) (return 8mm) I am going to put on a (8mm feed) and (12mm return) and ensure that there is no restriction at all in the return pipe as this is 1 of the possible culprits to this problem, if this still remains I am going to strip the fuel regulator and make sure the diapham is ok and all the other bits and bobs inside but after that I am stuck for ideas, I am very reluctant to think that it is the waste gate sticking however I may take a look if nothing else comes up.


Please let me know if anybody else has any sensible ideas or possible causes.

Thanks in advance.

snapper - 30/7/12 at 04:51 AM

Depending on the carbs fitted ( you don't say) wouldn't a rising rate pressure regulator defeat the float valves??

maccmike - 30/7/12 at 09:59 AM

^^ good spot

Autosri - 30/7/12 at 12:09 PM

Not really sure if it's applicable here but could it be a slight misfire when you leaned out he mixture as widebands see miss fire as mega lean maybe try setting the fueling by reading the plugs

borg230rover - 31/7/12 at 10:20 PM

Due to running the turbo you have to fit a regulator, because the fuel pump is high pressure without the regulator the pump would continue to flood the carbs, running it without the regulator is not optional. The old Renault 5GT turbo came out of the factory with carbs and s fuel regulator.

Misfire may account for the wideband reading a lean mix but it does accounr for it running mega rich which is the main problem, I will has a look at the plugs.

Not sure what the carbs are make vise? However they are off of standard R1 bike.

Autosri - 1/8/12 at 12:20 AM

reason i mentioned the misfire thing as im having similar problems with my nitrous oxide on my daily driver if i richen the mixture it sits at 10.0 on the wideband if i lean it off just a little it sitts at 18.0 i know this is not correct as the plugs show the correct mixture but with the extra fuel its making it easy for the plugs to fire but with the boost/nitrous the spark plugs arnt firing due to weak ignition so showing lean even though its not so fitted an ignition booster and it shows a rock steady 12.0 with the same jetting that showed 18.0

so have you looked at the plugs to see if it actually running rich or lean and ignore the wideband for a bit

BaileyPerformance - 2/8/12 at 08:53 PM

quote:
Originally posted by borg230rover
Mac R1 Turbo rich

Hi can anyone help me.

I have completed the build of my carb'd yamaha R1 Turbo Mac about 1500miles ago, it drives very nice and you wouldn't know of any underlaying problems that it had as I didn't until last week when I took it in for a rolling road tune.

Let me explain,

I drove about 40 miles to PDQ in Slough to get a roading road tune, the guy hooked it up to the rollers and gave it 3 good runs, after which he said to me the car is running dog rich so bad infact that the wideband sensor could not keep track of it and as soon as the car reaches 3000rpm the richness line goes way off the scale.

No problem he thought and changed the main jets to a more suitable size, checked the needle positions, fiddled with the mixture screws a little and then run it up again. This time the car was mega lean.

From that we though right we are on to something here the first jets 1.44 dog rich, the second ones we tried were way to lean 1.20 so lets try something in the middle so the changed the main jets to 1.32 smack bang in the middle.

Guess what it would barely run at all would rev a couple of times up to a max of about 5000rpm then cut out, would always start again though no probs.

We couldn't understand what the hell was happening.

We then decided to adjust the boost pressure on the turbo from 7psi upto 14psi (.5bar to 1bar) and every where in between but it made no difference (this engine has turbo pistons/rods/head studs/gasket etc) before anybody asks.

In the end we carried out 9 runs all of which were dog rich.

The rolling road guy reckons that the car has something else effecting the fueling a few ideas that he came up with was that the waste gate was sticking open and the car wasn't boosting properly, or the fuel pressure regulator was not working correctly. I personally thought that it maybe the fuel pressure regulator to fault but as of yet can't prove or disprove that, I have put a fuel pressure gauge in the fuel line and it does tick over at 3psi of fuel pressure which Jack Frost from Holeshot Racing recommends is the correct pressure, the fuel pressure does appear to rise quicker than the boost but they do end up at roughly the same pressure which will be causing a slight problem but not to the extreme that would cause such richness (i dont think)

I am about to change the fuel feed and return lines because at present I do believe that the feed line is a larger diameter than the return (feed 10mm) (return 8mm) I am going to put on a (8mm feed) and (12mm return) and ensure that there is no restriction at all in the return pipe as this is 1 of the possible culprits to this problem, if this still remains I am going to strip the fuel regulator and make sure the diapham is ok and all the other bits and bobs inside but after that I am stuck for ideas, I am very reluctant to think that it is the waste gate sticking however I may take a look if nothing else comes up.


Please let me know if anybody else has any sensible ideas or possible causes.

Thanks in advance.


Have a think about swapping too fuel injection, save scrapping an expensive engine. Carbs with forcd induction is hard to get close, not worth the bother when you can use mega squirt.

borg230rover - 2/8/12 at 09:01 PM

I could change to fuel injection but it would simply not be worth the money to do it, anymore bright ones.

BaileyPerformance - 3/8/12 at 09:06 PM

quote:
Originally posted by borg230rover
I could change to fuel injection but it would simply not be worth the money to do it, anymore bright ones.

You could do an efi conversion for less than £1500, cheaper than rebuilding the engine! That includes someone like me mapping it for you, anyway hope it works out for you!

[Edited on 3/8/12 by BaileyPerformance]

borg230rover - 4/8/12 at 04:55 PM

Thats very interesting, I had no idea that it was possible to change an engine running on carbs to fuel injection. Could you tell me more or do you have a contact number where are you based.

BaileyPerformance - 6/8/12 at 04:51 PM

quote:
Originally posted by borg230rover
Thats very interesting, I had no idea that it was possible to change an engine running on carbs to fuel injection. Could you tell me more or do you have a contact number where are you based.


Hello, have a look at our website www.baileyperformance.co.uk

We are in Telford, Shropshire (Midlands)

borg230rover - 6/8/12 at 05:05 PM

Couldn't see much in the way of bike engine work on your website however I was very impressed with 2.0L turbo zetec, what would be the cost of that sort of conversion be if I was to give you a seven style car with a standard 2.0L zetec in it.

BaileyPerformance - 7/8/12 at 07:23 PM

quote:
Originally posted by borg230rover
Couldn't see much in the way of bike engine work on your website however I was very impressed with 2.0L turbo zetec, what would be the cost of that sort of conversion be if I was to give you a seven style car with a standard 2.0L zetec in it.


There's a hayabusa grass car we did on megasquirt with jenvey throttle bodies.

The zetec conversion costs £3200 this includes all parts, installation and mapping. The actual engine remains stock, a 2.0L will make 250bhp on low boost, max safe power on stock engine 270bhp.

Let me know if you need more info.

borg230rover - 11/8/12 at 09:23 PM

What makes you think of scrapping the engine, and then you mention rebuilding the engine, there is nothing wrong with it just fuelling problem.
The hayabusa grass car you mention with mega squirt, that's 1 engine, that does really count as experience with bike engines.