What would cause this ???

GoldenMotor.com

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
Hey guys as most of you have seen I've got a cruiser fitted with with a regular china girl kit , now she has run well from day one , great acceleration but yesterday on the way home she started to bog out at the high end , has stalled out a few times it's as if she is starving for fuel , plenty of spark , plug is light brown so mix is correct , inline filter looks clean as a whistle , no air leaks anywhere , head bolts are tourked correctly but she seems to be suffering at the high end intermittently and I've noticed she is underpowered at very low gradients

I've done all the general checks but this one has me stumped ,I haven't checked the tank filter yet though

Any ideas what the problem could be , she has also become a tad hard to start from cold but once warmed up only misses or bogs out at the high end

Opinions GO ??????

Regards Henshooter
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
Just took her for a run , no leaks that I can tell but she won't idol ,just stalls out but seems to be ok at the high end now , ARGGGGG so confused as to what it could be
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
could it be a plugged muffler??
Not sure will have to look , she is smoking a lot compared to usual which tells me the mix is screwed up or maybe a ring has gone ,running her for 45 seconds left a small patch of oil on the road ( or grass in my case) , just don't understand how simply running well , sitting for 1 day and then being run again could cause such a problem ( she is a temperamental #*^%}+ at the moment)

I did notice the exhaust outlet bolts were a bit loose and I had some oil buildup on the head below the output ( the splattered type look) indicating a small leak from the exhaust but I've tightened that and rode for 2 mins ,no more oil splatter

I do apologise for so many questions ,I'm fairly limited where knowledge of 2 strokes is concerned and my previous builds have been without faults ( consider myself lucky )

So could a plugged exhaust cause this issue ???

I'll clarify the symptoms

First she started bogging out at the high end intermittently yesterday and didn't have the usual get up and go she has always had

Now getting her to the top end is a struggle but once there she runs ok ,still cruises at regular speed but is smoking a tad more than usual

After tightening the ex manifold bolts she idols somewhat ok

She is spitting more oil than usual IMHO

Help ,I feel like my belle is dying or very sick and every step I follow leads to nothing in improvement

Regards henshooter:-||
 

Theon

New Member
Jan 20, 2014
1,440
6
0
FNQ Australia
You have a second carb now, so that's easy to test/eliminate,
The seals, I know it's a new motor, but if you had seen what I have seen.
I sent a plug wire too , the original will unscrew, sorry the new one isn't black, I'd have a black one here some where.
Problem solving a motor goes,
Fuel?
Spark?
Compression?
if you have fuel and spark right, check your seals.
 

Dan

Staff
May 25, 2008
12,765
115
48
58
Moosylvania
Wouldn't account for the more then usual oil splatter but could or do you have an in-tank fuel filter?

Just a thought.
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
Wouldn't account for the more then usual oil splatter but could or do you have an in-tank fuel filter?

Just a thought.
Yes but can't check it till the Moro , got relatives coming to stay and don't want to stink of fuel on their arrival

Will check all options and get back to you all tomorrow

Thinking about it she only started playing up when I parked her up at a local shop right as it was flooded with school students ,hope one of those buggers hasn't contaminated the fuel

What would cause excessive smoke ,it's not a whole lot but enough to have a noticeable difference
 

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Yes but can't check it till the Moro , got relatives coming to stay and don't want to stink of fuel on their arrival

Will check all options and get back to you all tomorrow

Thinking about it she only started playing up when I parked her up at a local shop right as it was flooded with school students ,hope one of those buggers hasn't contaminated the fuel

What would cause excessive smoke ,it's not a whole lot but enough to have a noticeable difference
If you have a way to check compression that is what I would do at this point also, the extra smoke could be that it is running rich, your carb float may be taking in some fuel, an easy way to find out if the fuel filters are flowing good is to turn fuel valve off, remove small screw at bottom of carb fuel bowl and then turn fuel valve back on to see ifyou have a good flow of fuel, if the fuel flowsgood you know your filters are fine.

Map
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
I'm with map.Sounds like something going south inside...
Does it sound any different? I noticed my engine made more noise just before I pulled it from service for a bad needle bearing. Caught it before it destroyed the top end, but just barely.
 

Nashville Kat

Well-Known Member
Apr 20, 2009
1,501
55
48
Jacksonville, Florida
Have you made sure the choke is off?

At this point it may seem a stupid question-
but the choke is easy to brush down on-

I do this periodically, and even these days still can run sour for a bit wondering what's wrong- and it's always the choke has gotten pushed on.
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
Ok so relatives finally left ,time to correct this problem .

Checked carby for flow , pulled it off the motor ,took the bottom bowl screw out , turned on the tap and she has good flow .

Fitted the better CDI cable THEON gave me ,thanks again mate ,checked spark all is good there

Checked all filters to be sure all were clear

Pulled the exhaust to check for plugging ,all is clear but I did notice an excess ( well IMHO) on the manifold seal it's black but same consistency as the normal unburned oil see pic below

Yet to do a compression test , gotta locate a compression tester ( mate owns one just got to borrow it )

I've got a feeling she is running rich , would this cause the problem ???

The oil splatter was coming from the exhaust manifold seems stupid me forgot to check the anchors for tightness could this be the issue losing back pressure from the exhaust manifold ?????

Looked over all seals by eye ,they seem to be in good order

Thinking of draining breakin mix and running 35:1 mix ,currently on manual recomended 16:1 ratio

The only conclusion I have is she is running way to rich but why would she all of a sudden run rich when doing a chop test a day or two earlier she passed with flying colours

I did sit her for a day could have the oil in the mix settled to the bottom causing her to run rich ( don't see why though as I have to take her down a set of stairs to ride ergo she gets plenty of mixing ) or could it be fuel evap considering we had fairly hot weather and she was sitting in a hot room for a day that would increase the ratio but I wouldn't have thought that much maybe 1% tops

Going to try adjusting the carby pin but not sure which way to adjust her so any help there would be appreciated

Oh and what would a good compression ratio be , from memory the last build was 120 -130 and that bike run very well for 12 months with no issues whatsoever

This leads me to believe two possible issues either I've done a seal and have a loss of compression or the leak in the exhaust manifold was causing a lack of back pressure but would this make her run rich

I'm at a loss for the moment

:-||

Regards Henshooter
 

Attachments

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
Another case of 16:1....the Chinese instructions are WRONG!
Dump it out and switch to 32:1 or 40:1.
16:1 does nothing but plug the muffler and make a huge mess.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
While you have the exhaust off you need to grind or file the exhaust flange flat. Every one I've ever seen is warped from the welding process. That accounts for the blown gasket. You can tighten the fasteners all you want but if that flange is warped the gasket will burn/blow like the one you show in your photo.

Start by cleaning the gasket mating surface of the flange. When it is clean 'paint' it with a magic marker then run it over a sheetf sandpaper on a glass surface. You'll see the warp immediately. The ink will stay on the low spots and be sanded off the high ones. You want it flat, no high or low spots.

Check the cylinder mating surface while you're at it but generally they are okay. It is the welded steel exhaust flange that causes all the problems.
Actually the intake manifolds are the same. Lap those too for a good gasket seal.

Tom
 

Theon

New Member
Jan 20, 2014
1,440
6
0
FNQ Australia
switch to 32 or 40 to 1 of a good oil. 25 to 1 is for chainsaws/cheap oil. 16 to 1 is ridiculous.
If you wish to lean the needle, the clip should be second notch from the top, if not already there, try that. The jet I sent is checked to be .65mm the jet in your carb is likely .68mm.
I would also be trying this at some stage.
She'll be much happier once you drop the 16 to 1.
 

Henshooter

New Member
Feb 10, 2014
275
0
0
Melbourne au
switch to 32 or 40 to 1 of a good oil. 25 to 1 is for chainsaws/cheap oil. 16 to 1 is ridiculous.
If you wish to lean the needle, the clip should be second notch from the top, if not already there, try that. The jet I sent is checked to be .65mm the jet in your carb is likely .68mm.
I would also be trying this at some stage.
She'll be much happier once you drop the 16 to 1.
Dropped the 16:1 and am filling with 32:1 , putting her back together and snapped the exhaust end anchor bolt sigh looked at it and the weld to hold it in place was non existent ,like 1 mm of hold and the rest was flux , you can see by the black mark the weld job was pathetic

Don't know anyone with a welder and the closest engineering shop is 45 mins away and I've got cold weld but not sure that will work
Sigh need a new exhaust or a welder now ARGGGGGGG

upon looking at the exhaust manifold it is hella warped , it's out by nearly 4 degrees and theirs a huge bit of weld stick left just past the intake , I'm thinking I just had the bad luck of the apprentice working on the exhaust that day , looking at ordering an exp chamber exhaust , hopefully these issues will resolve this problem
Checked the pin slot she is in the correct location so will continue on the endeavour to diagnose the problem but with no exhaust ATM can't run her till the new one arrives

Cheers for the advice everyone it is greatly appreciated and I will keep you all posted on the progress

Regards Henshooter