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Expert stumped HELP. Gilera Purejet Engine.

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ddracer
Two Stroke Sniffer



Joined: 31 Oct 2006
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PostPosted: 08:36 - 08 Jul 2007    Post subject: Expert stumped HELP. Gilera Purejet Engine. Reply with quote
Hi guys,

Generally I help out in this forum but this time I have a question as this has me stumped.

I have a Gilera runner purejet 50cc in the workshop. It will not run, well it will for 3 seconds then stop. The diagnostic from the computer say there are no errors on the logged on the ECU and all the components test fine.

I have checked the air pressure from the pump and removed the injector pack and it looks to be working (smashing atomisation) the spark looks really good and the timing is ok no broken woodruff.

I have stripped the topend down and checked it and it looks normal no marks etc. I have even tried using the compressor in the workshop to supply the 5.5 Bar to the engine instead of the mechanical air pump just as a test but no result.

So there you have it Air-Fuel-Spark but still nothing.

Any Ideas?

DD Evil or Very Mad
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MaybeGuy
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Joined: 12 Mar 2007
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PostPosted: 11:19 - 08 Jul 2007    Post subject: Reply with quote
gaskets? valves? piston rings? pistons? the flywheely thing on the driveshaft that returns the piston?

im a complete amateur, ignore me Very Happy
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ddracer
Two Stroke Sniffer



Joined: 31 Oct 2006
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PostPosted: 11:25 - 08 Jul 2007    Post subject: Reply with quote
LOL Yeah thanks for that.....

Cheers Easy.
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Pete.
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PostPosted: 11:42 - 08 Jul 2007    Post subject: Reply with quote
What is the air the compressor supplies to the engine used for?
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ddracer
Two Stroke Sniffer



Joined: 31 Oct 2006
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PostPosted: 12:24 - 08 Jul 2007    Post subject: Reply with quote
It supplies 5.5bar of pressurised air for the fuel+Oil charge to the cyclinder. This is then mixed with ambient air in the crank cases.
I used to to check the primary charge air pump mounted on the back of the engine.
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SM.Morgan
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Joined: 04 Apr 2007
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PostPosted: 14:11 - 08 Jul 2007    Post subject: Reply with quote
So your saying in practice it should fire up, like said above look for things which might stop it turning over. are you sure that the injectors are ok, don't always rely on the ECU to tell you every problem, it might be faulty itself Wink
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ddracer
Two Stroke Sniffer



Joined: 31 Oct 2006
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PostPosted: 21:11 - 09 Jul 2007    Post subject: Reply with quote
SM.Morgan wrote:
So your saying in practice it should fire up, like said above look for things which might stop it turning over. are you sure that the injectors are ok, don't always rely on the ECU to tell you every problem, it might be faulty itself Wink


Yep was thinking the same thing will try to swap the injector pack and see what happens. The customers brother has the same bike so will give that ago.

DD
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ddracer
Two Stroke Sniffer



Joined: 31 Oct 2006
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PostPosted: 20:03 - 12 Jul 2007    Post subject: Reply with quote
Sorted it was the injector pack.
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Pete.
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PostPosted: 20:22 - 12 Jul 2007    Post subject: Reply with quote
Nice one Thumbs Up

I'm interested in the compressor set-up, can you tell me how it is mounted and driven please?
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Old Thread Alert!

There is a gap of 4 years, 47 days between these two posts...

joel.d
L Plate Warrior



Joined: 28 Aug 2011
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PostPosted: 13:25 - 28 Aug 2011    Post subject: backfiring Reply with quote
Hi All

sorry to be a pain as a newby but I'm at a loss. I have a runner 50 purejet standard but with a gianelli exhaust. Problem is that it backfires when cold or when I pull away from a junction or traffic lights, even when warm. Its a pain as it slows me down. Anyone any ideas? My dad and his friend have looked but not found anything but not to sure about this engine. Anyone any ideas as we're desperate

Thanks
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Nope.
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Joined: 16 Feb 2011
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PostPosted: 13:37 - 28 Aug 2011    Post subject: Re: backfiring Reply with quote
joel.d wrote:
Hi All

sorry to be a pain as a newby but I'm at a loss. I have a runner 50 purejet standard but with a gianelli exhaust. Problem is that it backfires when cold or when I pull away from a junction or traffic lights, even when warm. Its a pain as it slows me down. Anyone any ideas? My dad and his friend have looked but not found anything but not to sure about this engine. Anyone any ideas as we're desperate

Thanks


Right, well next time it would probably be better to make a new thread rather then dragging up an old one on a pretty much un-related subject.

But anyway, down to your problem. Since the Purejet is an injected bike, did you re-map it when you fitted the exhaust? The problem is likely to be that its running massively lean.

The two options you have are:

Having the ECU remapped by a profesional. This is likely to be expensive and is probably not worth whatever power gain it would give you.

The other option you have is putting the standard exhaust back on. This is probably the best option. It might not go very fast, but this is probably for the better since unless your 17 and the machine has been correctly re-registered then its illegal for you to ride. What would you rather do, ride around at 35 MPH for a year and then get a bigger bike/car or loose your licence now and have your insurance cost a fortune for the next 5 years.
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chris-red
Have you considered a TDM?



Joined: 21 Sep 2005
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PostPosted: 14:38 - 28 Aug 2011    Post subject: Re: backfiring Reply with quote
computid wrote:
The problem is likely to be that its running massively lean.



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Old Thread Alert!

The last post was made 14 years, 118 days ago. Instead of replying here, would creating a new thread be more useful?
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