Won't build boost under load??
- Thread starter RobertTrivanovic
- Start date
I only have a high compression head and I hit det a tiny bit when it got hot with that setup. Ps. I'm running pump gas which is why I got a different head.
T
Looking at you reed pics, those are not what are causing your issues.
I would pressure test the intake and exhaust system to check for leaks.
If you find no leaks, I would try lighter primary weights. My spool/boost building sucked when I went a bit too heavy on primary weight last season. Dropped a few grams, and she would light right up.
Also, compression had a HUGE effect on spool in my experience. We had two Silber pro's out in cooke a few years back. One with a stock head, one with a lowered compression PAR head for pump gas. The lowered compression sled took FOREVER to build boost compared to stock compression. Ever since that day I have been highly skeptical of any lowering of compression on a 2 stroke turbo for any type of on/off throttle riding types.
How much compression did you drop with the "turbo domes"?
Finally, simple issues can cause you to chase your tail big time on these sleds. IE broken primary or secondary springs, etc. Many times, when you remove the pipe, you will need to run the sled for a bit before the y pipe gasket re seats and seals back up.
I would pressure test the intake and exhaust system to check for leaks.
If you find no leaks, I would try lighter primary weights. My spool/boost building sucked when I went a bit too heavy on primary weight last season. Dropped a few grams, and she would light right up.
Also, compression had a HUGE effect on spool in my experience. We had two Silber pro's out in cooke a few years back. One with a stock head, one with a lowered compression PAR head for pump gas. The lowered compression sled took FOREVER to build boost compared to stock compression. Ever since that day I have been highly skeptical of any lowering of compression on a 2 stroke turbo for any type of on/off throttle riding types.
How much compression did you drop with the "turbo domes"?
Finally, simple issues can cause you to chase your tail big time on these sleds. IE broken primary or secondary springs, etc. Many times, when you remove the pipe, you will need to run the sled for a bit before the y pipe gasket re seats and seals back up.
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guessing head is not helping
FYI I run the stock 2010 ho head with push turbo. Works great with a splash of av gas. Many people told me to leave stock head on unless wanting to run big boost. Jeff at Dakota built my sled if that helps ya.
FYI I run the stock 2010 ho head with push turbo. Works great with a splash of av gas. Many people told me to leave stock head on unless wanting to run big boost. Jeff at Dakota built my sled if that helps ya.
How much compression did you drop with the "turbo domes"?
The high comp head is I believe 13.5 I'd have to double check that, and I don't remember exactly but I believe the new one is 11.3 if I remember correctly.
I don't have a crazy amount of weight in there even when it's not building boost it still ran 7300ish rpm. And I just had my primary apart and it looks ok.
The high comp head is I believe 13.5 I'd have to double check that, and I don't remember exactly but I believe the new one is 11.3 if I remember correctly.
I don't have a crazy amount of weight in there even when it's not building boost it still ran 7300ish rpm. And I just had my primary apart and it looks ok.
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N
is your waste gate working .
And I don't think it's a head issue because it's not that it built boost slow it simply didn't build boost.
How can I check? Just moving it with my fingers it seems fine.
N
tial waste gate ?
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N
i would take waste gate and biow off apart look at parts and clean them / look at all the boost lines aii so test boost tee
E
Not sure if the wastegate is the prob. or not, but my bud had the same issue and it turned out to be loose tolerances on the wastegate shaft. What would happen is the thing would open and stick there. Look closely as you get it to the wide open position and check to see if the flapper catches on the turbo housing in the spot closest to the wastegate shaft. We fixed it by removing the turbo and actually peening the end of the wastegate shaft to tighten it up. It was obvious as it hung up every other time you actuated the gate while unhooked. It was very sloppy. Has not troubled us again. I know, seems crude but it worked. Anyway, good luck.
I just got my new reeds today so ill put them in and take a closer look at my waste gate. Is there supposed to be a lot of resistance when just pulling it by hand? I can move it I believe all the way and it goes back no problem by hand but it almost feels to stiff to me, running 8psi.
So on hard pack it will boost? If you ride the brake will it boost in the blower pow? What are your egt or afr readings while at full throttle? You sure it's just not pig rich from the new domes.
It did boost the ride before on hard pack. Not sure on the break thing. My AFR at WOT was running way lean actually at first (14.2) until i tuned it and went slowly all the was down to 10.6 testing it along the way with little to no change.
The changes I did since it last built boost, added weight to the primary (Now pulling around 7300ish RPM maybe slightly more), and changed the domes.
Tomorrow I'm putting in turbo specific reeds, and ill order a new exhaust donut.
It has stiffer turbo springs on it too so it SHOULD be holding tight all around on the exhaust.
What would riding the break do?
H
10.6 is a little rich. Should be more around 12.5 at wot. For the exhaust just use high temp silicone to seal up your exhaust. Using your break will load the motor to help light the turbo.
G
closely examine the airbox all the way around, many times I have found that hairline crack along the bottom edge..
if you dont have an airbox and have the silicone tube splitter, be leary of internally splitting.
the silicone will delamintate internally and flap shut blocking all airflow when trying to get on boost. airboxs never do that..ask me why I have 4 on the wall for examples to prove how bad an idea they are..
if you dont have an airbox and have the silicone tube splitter, be leary of internally splitting.
the silicone will delamintate internally and flap shut blocking all airflow when trying to get on boost. airboxs never do that..ask me why I have 4 on the wall for examples to prove how bad an idea they are..
Hopefully Ill get to that over the weekend if I find time.
And how might I check that? It turns nicely and I don't see anything obviously wrong with it.
M
Have you looked at the turbine side of the wheel to see if there is any damage? had a friend who had similar issue and it ended up being all the fins were gone on turbine side of turbo
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