Garrett T25 Turbo Build

Thats the needles I put into my Mikuni VM36 and with the fuel pump running at idle I run 3 psi and with 10 psi of boost I have 13 psi fuel pressure so far I have no overflow from the needle being held open. Good luck with tuning I am having a hell of a time.
 
WALLY
You rode that bike with 10 pounds of boost??
I would think 4 to 6 pounds would be the sweet spot because you are still running higher compression pistons. You guys should call WISCO or JE and see if they would make you a set of 8 to1 compression pistons. Maybe they even have them who knows. I seen a guy a year ago with one of those little garrett turbos on a quad and man did that sucker run. What i was going to do was try and make the deck height higher with a taller base and head gasket to bring down the compression so the motor wouldn't work as hard . Ideal fror a turbo would be 8.1. The frame i was going to use was going to be stretched 5" in the middle so i could set back the motor and have the turbo inside the front tubes. The hayabusa i just finish up the motor for is 1441 with Turbo from orient in ny and should pull some numbers at the track and it winds up fast. Rods were $1000.00. My days going fast are OVER but you young guys all have the FEVER for speed. I always wanted to do over 200mph in 1/4 but too many street accidents made me a watcher. Fastest i went in 1/4 was 7:76 at 184 on a two speed Harley. Those were the days. Guys keep up the good work and i want to see some videos. Make a old man have a smile.
 
I do not want to steal this thread but no I have not even been able to get it to run well enough to ride. I am running a much smaller turbo ghb31. It spools extremely fast. I will soon start a build thread now that its almost complete, its been a 3 year process and I have some videos to put up.
 
Wallywheels, thank you for the input on the 1.5 needle and seats. Where did you source them? Also what pistons are you running? Also, are you running a single or dual carb setup? I would really like to see your build thread!:D
 
I don't like the dual carb setup because first they are CV vacume and you may have a problem with the slides with the force of air at higer speeds. I have always used flatslide METAL slides. I only ever had one carb (single carb) have the slide destroyed.I have had good luck with the 40 mm carb that you use on a harley. When i do build it i am only going with one carb. The smaller turbos do spool up faster but i personally would rather have that. I am not looking for land speed record just want to see if i can get more HP out of it. REMEMBER still got vibration around 70MPH out of these motors and maybe you are starting with 65HP and hopefully you can pull 6 lbs boost all day long and get anthor 20 to 30 HP more and i would be happy with that.
Here is what i had in this old mans head... WISEGUY 2 into1 Manifold puts carb on side of motor. Matched exhaust right to turbo maybe 6" pipes Turbo mounted in front of motor. Exhaust out left side of motor.Tube from Turbo to carb.Now you can pull oil from front tube and dump back into case. Single carb even distance from turbo and manifold for carb.It looks good on paper just got to do it.This is a basic setup i did on a Harley and worked fine had pleanty of air to cool turbo while riding and mixture was even.JUST MY THOUGHTS and i have seen others work but i want a bike that starts easy goes down the highway and not putting me on the side of the road pushing.
 
Ill give ya a teaser for my thread and I am using a single carb but it is a roundslide and I am weighing more towards a flatslide now. When I first built it I did not think of the pressure pushing up on the slide. So to combat the issue I ran a pressure line from a pitot tube in the pressure side of intake to the top of the carb slide and float bowl.
 
Sorry forgot to add the photo
 

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Wallywheels, you confirmed what my boss said at work. He had a couple polaris two stroke twins back in the day that he turbo'd and he had to run a boost line to the top of the carb to prevent the slide from sticking at wot. I thought that the hole for the needle and slot for the needle holder would be sufficient to allow pressure to equalize both above and below the slide. Either that or maybe run a stiffer spring :D Also, have you had to seal the top of the carb at the throttle cable to carb top joint? If so, did you just use silicone or a boot?
 
Here is the short video of one of the first attempts to run the bike. The battery was close to dead at the beginning of the video and the engine would break up whenever the throttle was opened. It kinda sounds like a two step launch control system was installed haha!

http://s1112.photobucket.com/user/plattey/media/VID_20130323_124209_366_zps7b20e367.mp4.html

Quick update: I found that the vm34 carbs I put in my old TX340 have 1.5 needle and seat assemblies so I installed those in the vm34's for the bike. Currently at my parents' for the holiday weekend and returning back to Osceola monday evening and will hopefully have time to install the carbs and do another trial run.

Happy Easter everyone!
 
Update: the 1.5 needle valves are installed and tested and work under 5 psi base pressure and didn't see any leakage or evidence of leakage thereafter. Also opened up the banjo bolt for the turbo journal bearing supply line to allow more flow through the bearings. Last and most certainly not least, the road test. When I first put it back together I forgot to plug the float bowl overflow barbs and whenever the turbo would start to boost, the fuel would get blown out of the carb and the engine would fall flat on its face. Plugged the float bowl overflows and took it for another run and wow! Boost came on in 2nd gear (first is too short and the turbo lag is substantial) and I let off the throttle at 5psi and when I did that the throttle cables lifted off the carb tops and got stuck. Throttle stuck at quarter throttle I had to shut it down and pull over to fix it. Temporarily used some zip ties to hold the throttle cable tops down until I can adjust the bov. Took it for another run and it peaked at 10psi. At that point I was grinning ear to ear. During these test runs I had removed the headlight to lighten the electrical load and I think I will just put a switch to turn the headlight on and off. Video soon to come.
 
WOW! sounds great and very smooth. In the video you had said you had an oil issue what was it and how did you fix it? on mine I have oil dripping from the exhaust side of the turbo not sure if it is bad rings or if my turbo seal is already gone or if I am just not getting enough oil return without an oil sump pump.
 
The oil issue was that the turbo wasn't getting enough oil. The auxiliary oil pump doesn't supply enough pressure to supply enough oil through the small oriface through the banjo bolt. Had to open that up. If you're getting oil out of the exhaust side, then the seal may need to be replaced.
 
I tapped a 1/8" NPT hole in the top and ran pre intercooler boost to it. I sealed the throttle cable with a rubber boot not sure if it is satisfactory or not time will tell. I believe a stiffer spring is in my future do they sell actual Mikuni springs or do I just source something like it? When I let off the throttle it stays open and slowly comes down so I def have an issue there. I also want to switch to a flat slide or (anything i'm open to suggestions) to eliminate these issues. We will see what comes first.
 

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