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General Two Stroke Talk / racer x race report
« on: July 17, 2013, 03:17:21 AM »
Good on you, are there pictures?
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17
General Two Stroke Talk / YZ 250 EFI
« on: July 14, 2013, 09:18:26 AM »
No one want's to take a risk in this financial environment. Remember to rotary engine debacle, late 70's.
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General Two Stroke Talk / YZ 250 EFI
« on: July 13, 2013, 12:32:47 AM »
Didn't you get the message, I sent the pigeon two days ago 
. After yesterday I'm more than happy for anyone to ride it, with Wayne's permission, I've been a bit nervous as to how it might perform in the real world.
Yes a bit muddy but central plateau drains well so still plenty of grip. TM, do you do any of the Epic Events rides? Be happy to meet you at the next event with a view to do a " bike test ". If you give it a bad review you will have to ride the Kawasaki for the rest of the day and I invite you to review that
. After yesterday I'm more than happy for anyone to ride it, with Wayne's permission, I've been a bit nervous as to how it might perform in the real world. Yes a bit muddy but central plateau drains well so still plenty of grip. TM, do you do any of the Epic Events rides? Be happy to meet you at the next event with a view to do a " bike test ". If you give it a bad review you will have to ride the Kawasaki for the rest of the day and I invite you to review that
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General Two Stroke Talk / YZ 250 EFI
« on: July 12, 2013, 11:26:27 PM »
This project was undertaken as " non profit " , a hobby, because I would like an EFI twostroke myself but no one offer an EFI bike. I waited for the OSSA, but noting seem's to be happening there so I decided to have a go myself and so far so good. I would be happy if Yamaha started to produce an EFI towstroke. Perhaps like this one or perhaps DI either way it would be a good thing, until this happens I'll continue on experimenting with what we have ( and with a bit of spare time perhaps finish the new 360 )!
I think manufactures still have a **** load of valves to sell yet.
I think manufactures still have a **** load of valves to sell yet.
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General Two Stroke Talk / YZ 250 EFI
« on: July 12, 2013, 10:46:57 PM »
I had the Kawasaki at Epic Events ride yesterday but didn't fire it up, too busy with the YZ's. We got to talking about how hard it would be to run the yz on ethanol fuel. Unlike a carb where it IS a drama to change, the YZ will only need the push of a few buttons, that instant.
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General Two Stroke Talk / YZ 250 EFI
« on: July 12, 2013, 10:37:35 PM »
Stu, put it this way, the EFI bike was by far the best bike for the conditions yesterday.
It's still early days in understanding what we have got, it would seem that the injection timing has a big influence on the way the power is delivered, bottom, mid range. I think from what we have found so far that the power curve can be manipulated at this lower middle range with still the same top end. Yesterday it seemed the "power band" as such was gone!
I think the bit of metal in the last picture was from a casting disaster some years back, I'm not sure how that got in there.
It's still early days in understanding what we have got, it would seem that the injection timing has a big influence on the way the power is delivered, bottom, mid range. I think from what we have found so far that the power curve can be manipulated at this lower middle range with still the same top end. Yesterday it seemed the "power band" as such was gone!
I think the bit of metal in the last picture was from a casting disaster some years back, I'm not sure how that got in there.
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General Two Stroke Talk / YZ 250 EFI
« on: July 12, 2013, 08:10:54 AM »
Weight? Throttle body is lighter than a carb but add fuel pump, small battery ( could be a capacitor ) and link unit. Flywheel and stator approx same weight, plus a little wiring. You are looking at around a Kg and a half extra. You won't notice it. Cost is still the big problem.
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General Two Stroke Talk / YZ 250 EFI
« on: July 12, 2013, 05:59:48 AM »
I couldn't help it, just wanted to see who was watching.
This is feed back from someone ( old ) that rides a normal YZ all the time ( and F9 ) so I'm just relaying what the EFI felt like to me to ride. There has been no adjustments from where you saw it on the dyno, still too rich up top.
If you like " rip, **** and bust" you will not like the EFI, it is more like a YZ250F but with more power! Smooth power delivery all over. If I wanted to win enduros I'd use this bike. Top end both, bikes are similar ( remember the EFI has still not been dyno tuned so there is more power to be had yet ).
You knew I was going to say this but, I like it.
There is video but I was in control of that and it seems half the time the camera was pointing up my nose, plus lots of mud, so we will see if there is anything to post when we down load it.
This is feed back from someone ( old ) that rides a normal YZ all the time ( and F9 ) so I'm just relaying what the EFI felt like to me to ride. There has been no adjustments from where you saw it on the dyno, still too rich up top.
If you like " rip, **** and bust" you will not like the EFI, it is more like a YZ250F but with more power! Smooth power delivery all over. If I wanted to win enduros I'd use this bike. Top end both, bikes are similar ( remember the EFI has still not been dyno tuned so there is more power to be had yet ).
You knew I was going to say this but, I like it.
There is video but I was in control of that and it seems half the time the camera was pointing up my nose, plus lots of mud, so we will see if there is anything to post when we down load it.
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General Two Stroke Talk / YZ 250 EFI
« on: July 12, 2013, 04:57:53 AM »
Well, finally I got to ride the EFI YZ at an Epic Events trail ride today, Taupo / Napier road. Rained all day hard, and bloody cold ( NZ winter ). Worst conditions for a test ride. Also took my standard YZ 250 as a comparison.
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Technical / Main bearing clearance
« on: July 06, 2013, 07:00:46 AM »
It also depends on the fit, 0.03 interference I would use C4, 0.01 to 0.02 you could use C3. I use C3 in all my engines and gearboxes. More than 0.035 ( mm ) is too tight and you will have bearing problems. I've just had to tweak an engine case out to 0.02 press as it was 0.04 press and kept having bearing problems ( main bearing ). I'm talking outside fit to case. You need to be able to feel clearance ( wobble the inner bearing housing a little bit ) on the bearing after it has been fitted to the case. C4 clearance is often used as a "fix" if cranks are not properly alined after manufacturing. Example, Rotax aviation engine ( twostroke ) has C4 bearings as they are only pressed to within 0.05 run out at the factory, poor manufacturing job in my opinion. You should be looking at less than 0.02 run out ( out of true alinement )max.
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General Two Stroke Talk / YZ 250 EFI
« on: June 25, 2013, 09:06:15 PM »
Bearorso, thank you for the encouragement, I have noting to hide in this project and we are just scratching the surface. As you can see we simply placed the injectors here for convenience. I wanted them to the rear of the cylinder but someone placed a reed block there. We now have a small oiler in operation ( you can see by the smoke as we are still running pre mix as well ). This will change shortly to oiler only, no pre mix. We made no adjustments on the dyno just ran it to see how it went. It's way rich up top. We do plan to go back with my carburettored YZ as a comparison and start making changes to the EFI fueling, EFI timing and ignition timing. So far this has been done by rider feel only. Yes computer power and hardware has come a long way since Bimota, it's a pity, they were ahead of the game. I'ts an interesting hobby ( getting out of hand ), I'm mostly posting here to show what can be done. Too may people just say it's impossible without having a close look first. The key will be getting the injectors placing right ( in the cylinder ) and the ultimate injector timing to reduce hydrocarbons out the exhaust, just air lose. There will be plenty of pictures ( inside and out ) of the new engine as it's finished and run.
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General Two Stroke Talk / EFI Bighorn
« on: June 24, 2013, 09:54:27 AM »
There is a video of the Bighorn on the dyno coming up soon, it's somewhat more " uncivilized "
The new engine is going to have to put out 65 or more (Crank HP), I want more than any 450F can muster!
This Bighorn has very old cylinder Tec on it I haven't done anything to the ports apart from cleaning the burs around the transfers and raising the barrel a bit. And widening the exhaust a bit.
The new engine is going to have to put out 65 or more (Crank HP), I want more than any 450F can muster!
This Bighorn has very old cylinder Tec on it I haven't done anything to the ports apart from cleaning the burs around the transfers and raising the barrel a bit. And widening the exhaust a bit.
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General Two Stroke Talk / YZ 250 EFI
« on: June 24, 2013, 09:46:52 AM »
No, this run was a bit of a **** up, I couldn't find the wire under the tank to put the RPM trace on with out taking the tank off. It was late Sunday afternoon, Dyno was tired as we had spent most of the day tuning the Bighorn. So we only had time to do some quick road speed runs. We are heading back with my standard bike as well as the EFI one for back to back tests. If I had remembered what colour the wire was out of the ignition box I could have clipped the trace on there, never mind next time. The rev limiter is cutting at 9000 rpm, although to be fair I don't think we were quite hitting 9000. The full throttle fueling is too rich I think but up to that point it's running real nice.
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General Two Stroke Talk / EFI Bighorn
« on: June 24, 2013, 09:39:11 AM »
It wasn't that good when it first went up on the dyno ( first run 42HP with a steep rough curve ), but after some fueling changes it's got good power spread. If I was to widen the exhaust and raise the exhaust to 190 degrees I might hit 46 ish HP. NO, just leave it alone and ride it!!