# Doesn't wind up-could 100 lbs comp be the reason?



## GlynnC (May 9, 2009)

Working on RedMax trimmer --still the same one that I wrote about a few weeks ago--carb parts flying through the air!! It starts good, runs up to about mid speed but no more. Been thru the carb twice (flying part from other thread was the filter screen), decarboned exhaust port, burned carbon out of muffler, chgd plug, fuel filter, gas lines. Compression is 100--tested with a new high quality guage.

*Could the 100 lbs compression be the problem?*

Funny thing, my client called the dealer where the RedMax was purchased--the person who answered said the RedMax's were made to only rune on ethanol 85 gasoline!!!!!


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## pyro_maniac69 (Aug 12, 2007)

how does the cylinder look?


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## ossaguy (Dec 3, 2008)

100 psi is on the low side.I see a lot of Redmax trimmers that have the piston rings stuck in the piston grooves because of carbon.Leaking base gaskets too.
Are you sure that the lines are not over-extended? 
With it just being 2 screws that hold the cylinder on,it's pretty easy to pull the cylinder and know for sure.Worn piston skirts will cause lower rpms/power also.
In my experience,100 psi isn't going to make it not go above half speed.Usually it's a muffler,exhaust port carbon issue,but you've already ruled that out.
If you blow air into the muffler,does it easily flow out? Sometimes you can get a big chunk block the passage right before it gets to the arrester screen.Sometimes I'll try it for a second without the muffler to see what change in rpms it makes.
Is it a strato-charged model? The early ones had coil problems where they wouldn't advance correctly,so it couldn't get much higher than low speed.Just something to consider.I've seen it before where guys will change lots of parts,and have the internal timing defect going on in the coil.
Was it running OK before the carb was taken apart,or do you know the history of it? If it's running real rich,it won't rev.If It's got the common problem of dying unless you choke it,that's the opposite,at lean.
Redmax products are not designed for e85 as far as I know,as is any other manufacturer.Most make a point to state that problems caused by running e85 are not covered under warranty.
I hope you get it solved!
Steve


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## GlynnC (May 9, 2009)

Thanks guys for your responses--it seems I've had the RedMaxs from hell this year. 

This RedMax was brought to me because it wouldn't wind up. The first thing I always do is cut the lines shorter--commercial guys seem to like to reach the next county with their lines. Still wouldn't wind. I didn't think to look at the piston when I cleaned the exhaust port--not much carbon. This customer runs Shindaiwa oil and I never see carbon build up in his epuipment.

This is a strato charged trimmer--has stuff behind the carb that I don't understand--always hope theres nothing wrong with it.

Tomorrow, I'll pull the muffler, look at the piston, blow air thru muffler, and maybe pull piston and check rings. I don't think I mentioned earlier, but I've checked for air leaks with choke cleaner while running--no change.


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## Deathrite (May 21, 2009)

as a Redmax dealer i can say for sure they are NOT designed to run on E85. Redmax has released notices that they should be run on FD rated oil and 89+ octane gas. 
as for the problem i can tell ya what i have seen cause that.
a clogged spark arrester. the oil you list (from what i hear) is good enough oil that i would think this would not be an issue. 
small bits in the carb holding the gaskets slightly open has been an issue with a few units. if there is a round plastic part behind the carb with a fuel hose running from it, thats a new feature i have not seen much of. 
have you checked compression after the carbon cleaning? the rings in the Redmax seem to like to wear in the older units. 
i have also seen the reed valves (located on the sides of the engine) wear out and "leak". if you suspect them i highly suggest replacing both at once. 
if i think of anything else before you fix it will post again. good luck


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## GlynnC (May 9, 2009)

Deathrite, this is one of the RedMax's that has the small "fuel line" behind the carb.--don't know anything about the function of this line! I have not rechecked compression since decarbon process--will do that tomorrow.

Heres the latest--removed muffler today, piston and rings have no scoring or burned marks--look great. I sprayed SeaFoam Deep Creep on the rings and into the sparkplug hole--let set for an hour. Spark arrester has been punched out--common in this area! Used compressed air to blow out muffler--several good sized carbon chunks came out, so I burned out the muffler again with mapp gas torch.

Reassembled!

It now runs much better--almost acceptable. It pulsates a slight amount at WOT. I'm suspecting it might have had carbon in the ring grooves--but it could have also been the carbon chunks in the muffler--will blow out all mufflers in the future!

Probably will ask owner to give it a try.

Thanks for the help!


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## Deathrite (May 21, 2009)

yeah one of the new ones. i have not been able to play with one of those too much... and the little i was able to i did not get too deep into it. i will say be VERY careful if you feel the need to take that little round front part off the mystry part. behind there is just a diphram pump. i would guess it helps in the air flow or fuel flow. 
have seen carbon bad enough in the muffler to cause running WOT issues in Redmax units. 
i have put a cap full of auto carb cleaner in the gas and let it run the gas out. had to do that in an Echo yesterday. helped some but just too much carbon. have to dismantle and clean more. 
letting the SeaFoam sit longer might help too.


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## ossaguy (Dec 3, 2008)

The hose/diaphram part is called the "MaxAccelerator Pump",and if I understand what our rep said,is that it allows the factory to get rid of the midrange bog that the emissions engines have.He said that CARB/EPA testing procedure is to take the emissions reading at idle speed,and wide open only.Mid range is not tested,so they can tweak it so it won't be gutless,by richening it up in that range,yet still pass the test.
Haven't had one in for service yet,but have seen them go out the door.Pretty neat idea,I think.


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## GlynnC (May 9, 2009)

Been running it today with Sea Foam in fuel--no noticeable change yet. I did lengthen the line out like the commercial guys run it--the pulsating went away as soon as it was put under a load. Is it possible that the pulsating is an RPM limiter of some type? Doesn't seem like it's running that fast, but sometimes it's hard for me to tell just by listening to a unit I haven't used when it was running good--don't have a way to check RPM.

Don't plan on getting into the stuff behind the carb--out of my league--wouldn't know what I was looking at, or if it had a problem!


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## ossaguy (Dec 3, 2008)

A digital tach is a valuable tool to have.If the coil has a rev limiter built in,the tach will show ok readings up to that point,then it kinda goes nuts.Most limiters on line trimmers kick in around 9500 rpms.
I have had several different brands of units this year that had the ignition governors out of spec,so they would kick in down around 6000 rpms.With the new coils,they were back up in the 9500 range.
The basic model of tach that an Echo dealer can order you,or the one from a Stihl dealer is the least expensive that I'm aware of.
I think you can get a B&S 
"Tiny Tach" hour meter for even less, ( I think I saw one at Wal-Mart even)and it has a tach built in.It's not as handy though,because instead of pointing it at the plug,the little wire needs to be wrapped around the plug wire,( if I remember right.)
Take care,
Steve


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## Deathrite (May 21, 2009)

is that echo and stihl one non contact tachs? if so where can i find one? been looking for one for a few months and found nothing. 

Ossaguy- yeah that sounds about right. our rep didnt talk about them much.. think they are afraid the EPA will get wind and start checking mid range 

and yeah the tiny tach has a wire you have to wrap around the spark plug wire. 

which units have you seen the rev limiter in the coil?


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## ossaguy (Dec 3, 2008)

The Echo & Stihl are inductive,just hold away from the plug lead about an inch.The Echo one is shaped more like a thin cell phone,the Stihl one is smaller,about the size of a credit card.( It's almost too small...easily dropped.
Dropping them kills them,so after I replaced my last Echo ,I took 2 Toro 2-cycle airfilter foams,# 81-0100 I believe,and made a cutout in between them to fit the tach,then glued the halves together and trimmed down a bit.It has a cutout to view the readout screen.
Sorta like a rectangular Nerf Ball,so it can be dropped now,and doesn't get damaged.Still reads the same inside the foam.
A cool new tool that Echo sells( maybe others too ) is the SparkStar.It's a key fob that you just point a few inches away from a spark plug,and the LED light flashes bright if it's got spark.Pretty handy to whip that out on a 2 cylinder engine that sounds like it's on 1 cylinder.It doesn't load the system like a true spark tester does,so it's not a substitute for a true tester,but you can wow your customers by walking by their running machine and point it so they see their spark.Kinda handy,I think.
On Monday,I can post the part numbers if you like.
The rev limiters that I have seen go lately are on Stihls and Echos I had a string of units over a few week period that were estimate nightmares.They don't run,yet have great ignition volts,and ok compression,but the fuel systems are all wrecked from stale gas.
The scenario is maybe like 6 months prior,they would run,but low rpms.The owners would stop using the unit because of it,and bring it in later after the gas went bad.So changing the obvious fuel system parts gets that right,but then only to discover the coil's governors are bad so poor rpms.In most cases the parts warranty but not labor,making for headaches.Man,I had like 3 a week,for about a month it seemed.Gotta love it!

Take care, Steve


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## ossaguy (Dec 3, 2008)

Deathrite said:


> is that echo and stihl one non contact tachs? if so where can i find one? been looking for one for a few months and found nothing.
> 
> Ossaguy- yeah that sounds about right. our rep didnt talk about them much.. think they are afraid the EPA will get wind and start checking mid range
> 
> ...





Just in case you wanted the part number for the Stihl & Echo tachs,

Stihl # 5910-850-1009

Echo # 99051130017

Take care,
Steve


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## Deathrite (May 21, 2009)

thanx Steve. will see if we can afford those 
and interesting about the rev limiters. we ar enot Stihl dealers so dont get any of those really. no way for us to get parts except through a dealer. we can get alot of Echo parts.. but not tried the newer ones. most we see are the older ones, 4+ years.


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