Notices
MVVS Support Get support from 3 qualified MVVS Forum Hosts. Dar Zeelon, representative from Israel. David Moen, representative from Canada. Pe Reivers, representative from Netherlands.

MVVS 45cc RPM Dropped

Old 09-16-2008, 04:24 AM
  #1  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default MVVS 45cc RPM Dropped

Hi, Last month I tached my engine with JXF 22 x 8 and I got 6800 rpm, but 2-3 day ago I tached again and I only have about 6000 rpm, I try to tune back the engine and cannot go higher. Any idea what went wrong ?
Old 09-16-2008, 04:56 AM
  #2  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: MVVS 45cc RPM Dropped

To be honest, no.
Loss in power can have so many causes you could fill an encyclopedia with it, and it is not possible to diagnose over the 'net with such meagre data as you provided.
My advise: If all the obvious, like carb setting, fuel supply, clean exhaust system etc. seems OK, send the engine to MVVS for maintanance.
Old 09-16-2008, 06:49 PM
  #3  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

thanks pe
Old 10-05-2008, 07:38 AM
  #4  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

Hi pe, i just wondering any possibility cause by the ignition ? my ignition produce only little spark.
Old 10-05-2008, 03:39 PM
  #5  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: MVVS 45cc RPM Dropped

That would be guessing. Like I said, too many reasons can cause this.
Old 10-08-2008, 08:34 AM
  #6  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

Take out the plug and saw inside, carbon build up almost 1mm thick
Old 10-08-2008, 01:12 PM
  #7  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: MVVS 45cc RPM Dropped

In that case, you probably had:
set the engine too rich, maybe even on the wrong oil.
you need to clean out the engine, best done by running carbon remover mixed in with your gas. This is sold in the better automotive shops
Fit a new plug.
You also need to clean out the muffler, which probably is coked up. Oven carbon cleaner may do a good job there.
Old 10-08-2008, 08:43 PM
  #8  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

thanks Pe, will do things that you mention and hopefully will gain back the RPM
Old 10-10-2008, 08:50 AM
  #9  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

Open and fond piston ring stuck, try to remove and it was broken, already change to new piston ring, should I break in the engine again ?
Old 10-10-2008, 04:06 PM
  #10  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: MVVS 45cc RPM Dropped

With the ring broken, you also should have noticed a sharp drop in compression.
Yes, please run in the engine again with a bit of extra oil (like 3%), but not too rich! The plugh must not be black.
Running in a new ring may take a bit longer than in a new engine, so be patient. Change throttle settings frequently, and avoid prolonged full throttle running for the first gallon.
Old 10-16-2008, 03:42 AM
  #11  
k_jitsu
Senior Member
 
Join Date: Jun 2005
Location: MadridMadrid, SPAIN
Posts: 105
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped


ORIGINAL: pe reivers
...
Running in a new ring may take a bit longer than in a new engine...
Why?
Old 10-16-2008, 04:03 AM
  #12  
zul_cessna
Member
Thread Starter
 
Join Date: Sep 2007
Location: Kuala Lumpur, MALAYSIA
Posts: 50
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

Pe, can the ignition battery effect the RPM, I was using 5 cells previously but now change to 4 cells, will this makes major effect ?
Old 10-16-2008, 09:48 AM
  #13  
pe reivers
Senior Member
 
Join Date: Jan 2002
Location: Arcen, , NETHERLANDS
Posts: 6,571
Likes: 0
Received 2 Likes on 2 Posts
Default RE: MVVS 45cc RPM Dropped


ORIGINAL: k_jitsu


ORIGINAL: pe reivers
...
Running in a new ring may take a bit longer than in a new engine...
Why?
because now all rubbing surfaces are smooth and shiny, and have work hardened slightly, especially the lower ring land in the piston.
Pe, can the ignition battery effect the RPM, I was using 5 cells previously but now change to 4 cells, will this makes major effect ?
Probably not, if the engine runs OK. It depends which type of ignition you have. Vlach ignitions run very well on 4 cells.
Old 10-17-2008, 04:07 AM
  #14  
k_jitsu
Senior Member
 
Join Date: Jun 2005
Location: MadridMadrid, SPAIN
Posts: 105
Likes: 0
Received 0 Likes on 0 Posts
Default RE: MVVS 45cc RPM Dropped

Thank you, Pe

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Manage Preferences - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.