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Engine pounding ?

Moderators: Curt!, Pa

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ama121

Posts: 16

Joined: Tue Nov 20, 2012 10:36 am

Post Sun Jul 14, 2013 3:24 am

Engine pounding ?

Hi,
Have a stange new thing start hapening this week.. :(

When i´m driving above 30 miles/h speeds and give it to much trotel the Engine starts pounding,
:shock: Whene i ease the trotel it disapers. when i use the trotel slowly and easy= no problems

feels like mix is to leen... i`ve tried to upp and down on main, pilot and nedle, but no diffrence..

Have i destroyed the bearings allready?? I know that mainshaft bearings there set upp i bit lose..

Anybody recognice this? :oops:

Engine is a new build: 4 7/16 stroker, mikuni 34, std cams, 5 alu heads, comp is about 6:1 , 85 psi

Have had some problems with jetting the mikuni, now it is : 200 main, 30 pilot, 6dh4 nedle,

Robban/Sweden
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Pa

Site Admin

Posts: 4720

Joined: Sun Mar 12, 2000 1:01 am

Location: Ohio USA

Post Sun Jul 14, 2013 11:01 am

Re: Engine pounding ?

This is just an educated quess on my part but I thing the bearing are set to loose.
<<

Tim 435

Posts: 741

Joined: Mon Sep 01, 2003 12:01 am

Location: Pa. , USA

Post Sun Jul 14, 2013 2:18 pm

Re: Engine pounding ?

Not clear on the pounding definition, could it be pre ignition engine knock or is it more profound ?
Vintage roadracing, Class C, AHRMA # 335
<<

woody

Posts: 492

Joined: Mon Apr 15, 2002 12:01 am

Location: Wa, USA

Post Mon Jul 15, 2013 10:27 am

Re: Engine pounding ?

My 45 used to make a similar noise when the transmission mounting bolts came loose.
<<

ama121

Posts: 16

Joined: Tue Nov 20, 2012 10:36 am

Post Tue Jul 30, 2013 2:38 am

Re: Engine pounding ?

Sorry about the slow reply. Been away on from home and didnt internett.

Engine pounding? Or maby Nocking i might say.. :?
Gearbox and trans is firm and ok..

I think i might have found the problem :cry: adjustment of carb and ignition

Just got the manual from "victory mikuni vm tuning"
It spred some light in the darknes.
Folowed the instruktions and:

The needle jet is to big :oops:
So i put the needle on max lean and lowered the flowt hight
I got better but mid-range is still way to fat.
Ordered some parts..

New question :?:
Sould the ignition be full retadred or full advanced when
Adjustin the ignitniton buy the book.
Dont realy anderstand what they mean in the book...

Reg
Rob
<<

GuS

Posts: 312

Joined: Sat Apr 28, 2001 12:01 am

Location: Bergen, Norway

Post Wed Jul 31, 2013 4:31 pm

Re: Engine pounding ?

To adjust the air and idle screws I have had best results setting the ingnition fully retarded.

GuS
<<

RUBONE

Posts: 381

Joined: Fri Nov 30, 2007 7:24 pm

Post Wed Jul 31, 2013 9:23 pm

Re: Engine pounding ?

To adjust the IGNITION,
First adjust the points gap on the highest point of the points cam. Easiest to do it on the wide lobe. Set at .022.
After the points gap is correct, set the ignition timing.
The timer needs to be FULLY ADVANCED.
Set the timer so the points just begin to break open as the timer hits the full advance stop on the compression stroke of the FRONT cylinder with the timing mark centered in the hole. Do this by rotating the timer base, do not change the points setting.
<<

GuS

Posts: 312

Joined: Sat Apr 28, 2001 12:01 am

Location: Bergen, Norway

Post Thu Aug 01, 2013 3:33 pm

Re: Engine pounding ?

Ooops. Rubone. You're right.
I answered a question Rob did not ask.

GuS
<<

GuS

Posts: 312

Joined: Sat Apr 28, 2001 12:01 am

Location: Bergen, Norway

Post Thu Aug 01, 2013 4:32 pm

Re: Engine pounding ?

Robban.
It would be interesting to know the final jetting once you get there.

My next stroker is in the pipeline and I'm considering using a 34mm Mikuni on that one.
When doing the stroker i have now I got a 36mm. After jetting i realised I needed to play with the low speed circuits to get it at it's best. Doing 120km/hours I still only have a little over 1/4 throttle. Main Jet is not into play at that throttle opening...

GuS
<<

ama121

Posts: 16

Joined: Tue Nov 20, 2012 10:36 am

Post Fri Aug 02, 2013 5:28 am

Re: Engine pounding ?

Tanks for info :D
I have adjuster ingition now (buy the book).
Runns nice and good up to 1/3 throttle.

one thing.. when letting go of the throttle in speeds around 30 mils/h (3:rd gear) im getting bangs from the muffler :(
Is it still the ignition or the needle-jet thats is to big :?:

GUS
Yes i will let you know, i;m actuali following the guidlines from the victory Book..
<<

wilko

Posts: 159

Joined: Fri Jan 15, 2010 7:36 pm

Post Fri Aug 02, 2013 6:55 pm

Re: Engine pounding ?

Manifold leak.
<<

ama121

Posts: 16

Joined: Tue Nov 20, 2012 10:36 am

Post Tue Aug 13, 2013 4:03 am

Re: Engine pounding ?

GUS!

My settins for the moment, only tested it for a short time.
Bike runs much better then before, main problem was the jet needle.
Have not tryed whit 159 p6 or 6dh3.

Jet needle 159 p4
neddle 6dh4 on third clip
air jet 1.0
main 260
pilot 3.0
<<

GuS

Posts: 312

Joined: Sat Apr 28, 2001 12:01 am

Location: Bergen, Norway

Post Sun Aug 18, 2013 3:39 pm

Re: Engine pounding ?

Robban. Thanks. I did not fully understand. Did you change the needle jet from P-6 to P-4?
GuS
<<

ama121

Posts: 16

Joined: Tue Nov 20, 2012 10:36 am

Post Tue Aug 20, 2013 5:11 am

Re: Engine pounding ?

Gus!
I was Q-2 needle jet orginal setting that came whit the carb.
Will test whit P-6 later this week.

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