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EG 295 questions

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well last fall I toasted my topend in my 03 yz250, apparently had a slow head gasket leak and neglected to keep an eye on my coolant level. it ran fine for a long time and then I guess it finally ran out. well my cylinder now needs some attention and I have been researching Eric Gorr's 295 for some time and like what I see about the mo-better porting option.  I just had a couple questions to get this thing ready to send off as soon as my income tax return hits the bank. I know I send him my cylinder and head, I havent touched my powervalve besides disconnect that arm. I put the bolt that hold the arm back in place and put the cover back on the cylinder.  Is this ok or do I need to take those things back off? and do I need to bolt the head back on for shipping?  and also I am assuming I for sure pay shipping TO him but is return shipping included in the $660 price tag?  I am really looking forward to getting his BB and get back on my yamaha.  I will be using it for hare scarmbles and some MX every now and then and with all the hard pack clay around here I like the smoothness of a 4 stroke but the light feel and cheaper rebuilds of a 2 stroke, and the mo better tuning sounds like a happy medium between 4 stroke smoothness and 2 stroke fun.  And I besides if I miss that snapiness, I have an 05 rm 250 that will rip your arms off when the power hits, very difficulty on hard pack but so much fun when you go somewhere with plenty of grip.  now if I can only get my taxes back before the government decides not to pay anybody because they cant get their crap together

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You can get all the info you need on his website.

I am pretty sure I paid the shipping both ways when I sent cylinder and head to him for a 295 kit.

leave the cover on the side off just like it is when you take it off the bike. Leave all other covers on the cyl. along with the entire Power valve assm. I put my head on minus o-ring with 2 nuts holding it on. I double boxed mine for extra protection but it probably isn't really needed.

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Like others have said you leave the powervalve alone, just unbolt the link arm. Bolt the head back on too when you ship. I thought return shipping was included in the price, I'm sure it's on the website though. 

 

While you're at it you should have your slide cut by him to reduce the 'hit' since you're looking for more 4-stroke smoothness, when I had my mo-betta done he did it for free.

 

Well, with the mo-betta your arms will definitely still get ripped out but that 'hit' is because there's so much more overall power.

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He has to to cut the entire valve assemble which is the main valve up front and the ones on the side so leave it in one piece. I would clean it up as best you can because there could be a lot of spooge pooled up in the power valve and I am sure eric probably doesn't like a smelly messy cylinder when he unpacks it.

 

You are going to love a Mo-betta...I would get the same one again in a heart beat if I started all over with a 250.     

Edited by primerib108

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Carb cleaner will work fine. Or just pop the power valve cover off a slop up the pooling sooge with a rag and tilt the cylinder on the side where the vent tube is to let it drain over night.

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haha yeah the mo better is a goofy term to use I agree, you can pick porting for more bottom/mid, more mid/top, or the "mo better" that makes a more broad powerband over the entire range (so I've read never ridden one). hopefully going to get it shipped out tomorrow I got may tax returns in the bank today, now I just gotta grab some carb cleaner and a couple boxes, so more than likely it will be thurs before I get it sent out.  Hopefully it won't take the possible 8 weeks he says on his site since this is his peak season (amateur off season). I would like to have some time on the bike before my first planned harescramble on april 6th.  I have a few things to do to the bike in the mean time (fork seals, silencer repacking, carb cleaning, an probably some other things I can't think of right now)  really looking forward to getting this thing going again.

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Fyi... while cleaning the carb consider changing the jetting too. You will most likely need to go leaner. Look at EG web site or search on here for ball park jetting specs. Also check out the condition of your reeds.

I have the mo-betta porting on my EG295. It is just what it says.

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A few little tips I can offer:

- Until it has torque right across the rev range, with no hit, no hesitation and good over-rev, then don't stop tuning it.
- Keep the squish clearance tight. Then use enough head vol for the fuel you use.  eg. I use a single layer metal head gasket.
- Order a new kick starter, if your's isn't healthy.

If you think a YZ250 has broad power compared to your RM250, then your 295 has the potential to blow your mind.
 

I've ridden a few stock YZ250 motors. The mo betta 295 should be able to produce  at least 100% (double) the torque off the bottom. Same mid. Longer over rev. Overall much broader and way less shifting compared to what we do with a stock YZ250 to get into or stay out of the mid range power.

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^^Agreed^^

 

It pulls and pulls throughout the throttle range and when tuned right and can easily keep up with the 450f's. You will chase some brass for the first little bit because they are finicky to jet....absolutley worth it though. An RB modded PWK carb was the icing on the cake for me and improved an already awesome engine.

Edited by primerib108

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He also likes for you to put the cylinder in a bag as well so it doesnt leak all over the box. I had to go from a 50 to a 55 pilot to get the throttle to stop hanging. Eric actually recommended 55 N3EJ3 188! Im sure that the needle is a half or even a full clip rich and the main should be closer to a 175 (remember it is 30 degrees outside) The broad smooth powerband gives MUCH more bottom but mine still hit pretty hard in

the mid range but that is most likely because the weather has not allowed me the time to jet it right. Make sure you check the last page of the order form for whatever specials they are running now. I paid return shipping but it was only 22 dollars ground.

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A few little tips I can offer:

- Until it has torque right across the rev range, with no hit, no hesitation and good over-rev, then don't stop tuning it.

- Keep the squish clearance tight. Then use enough head vol for the fuel you use. eg. I use a single layer metal head gasket.

- Order a new kick starter, if your's isn't healthy.

If you think a YZ250 has broad power compared to your RM250, then your 295 has the potential to blow your mind.

I've ridden a few stock YZ250 motors. The mo betta 295 should be able to produce at least 100% (double) the torque off the bottom. Same mid. Longer over rev. Overall much broader and way less shifting compared to what we do with a stock YZ250 to get into or stay out of the mid range power.

What is your squish and head volume set at? What fuel are you set up for? I am in the process of fine tuning mine. Mine was setup for pump fuel. I have 240 lbs compression with dbl layer steel head gasket. My squish is at. 071. I know that is too high. I know I can go to a single layer and get my squish to. 061 but I am afraid the compression will be too high for pump fuel. I have tried to catch Eric on the phone several times but haven't caught him yet. Just wondering what others are set at.

Thanks

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What is your squish and head volume set at? What fuel are you set up for? I am in the process of fine tuning mine. Mine was setup for pump fuel. I have 240 lbs compression with dbl layer steel head gasket. My squish is at. 071. I know that is too high. I know I can go to a single layer and get my squish to. 061 but I am afraid the compression will be too high for pump fuel. I have tried to catch Eric on the phone several times but haven't caught him yet. Just wondering what others are set at.

Thanks

I didn't notice any difference between a single and a doube gasket.  

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I didn't notice any difference between a single and a doube gasket.

Do you know what your squish is set at? What is your compression in PSI? Are you running pump 91-92 oct. gas?

Each gasket is 0. 010" thick. So using one instead of two will make the squish tighter and bump the compression some too.

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Do you know what your squish is set at? What is your compression in PSI? Are you running pump 91-92 oct. gas?

Each gasket is 0. 010" thick. So using one instead of two will make the squish tighter and bump the compression some too.

 

I could not tell you the squish measurement but Eric cut my head for 94 pump gas (with ethanol) and an atltitude of 4000ft. Last time I did a compression test I was 225 PSI and that was on my first top end with about 40 hrs. My second top end kit I ordered from Eric came with a single gasket but kicking it over and the power delivery feels the same. I should do another compression test since I am around that 40 hour mark and compare the two. The only difference I can tell was I had to drop my pilot to a 42 from a 45 and bump up my main from a 175 to a 178. A slight compression boost might have that effect?

Edited by primerib108

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What is your squish and head volume set at? What fuel are you set up for? I am in the process of fine tuning mine. Mine was setup for pump fuel. I have 240 lbs compression with dbl layer steel head gasket. My squish is at. 071. I know that is too high. I know I can go to a single layer and get my squish to. 061 but I am afraid the compression will be too high for pump fuel. I have tried to catch Eric on the phone several times but haven't caught him yet. Just wondering what others are set at.

Thanks

I'm using the single metal gasket. My squish is at 1.60mm. 63 thou.

Head vol not measured. Sorry. But read on.

My comp was at 245 psi when rings were new.

My fuel is Aus 98 pump.  That's about the same as 94 in the US.

After 51 hrs I have no signs of detonation. Piston crown and head inside looks great. Golden tan and spotless when I checked recently.

Motor runs awesome.

 

I never ran it with the double layer gasket! That would have put the squish at around 1.85 which is way too wide. I knew that (with most/any 2 strokes) a wide squish meant hesitation and fussy jetting. No fun at all.  I know that too tight can mean deto, rough off idle and RPM surging. I thought I'd give it a go with a single gasket, and got lucky.

 

I'm no engine builder! But I think it's pretty simple to get one of these things right. EG does the magic with the porting.  Note that it's not always a case of bolt on and go. Same reason that stock YZ250 motors differ a lot - there seems to be minor tolerance errors in the Yam motor, and EG cannot predict these. So I assume he (and Yam with the stock setup) has to be conservative and error the squish on the wide side, rather than letting it be tight.

1. Get the squish right. By machining the head or changing the cylinder height. Option depends on how high or low your want your ports and how high/low you want your peak torque.

2. Get your head vol right to avoid deto or allow practical starting. 245psi with Aus 98 works. But it's hard to start.

3. Set your spark timing. Retard for less mid hit and broader power.

4. Play with jetting, and pipes. Jetting compared to stock is typically one size smaller on the pilot and main, but keep your half throttle jetting (needle clip) on the rich side to get good progressive and instant roll on torque.

 

Result is an amazingly versatile motor. Torque up steep hills at silly low RPMs in 2nd, or comfortably blast along side 450s out of corners on sand tracks. I use 14/48T sprockets and don't have to shift much more than on my KX450F. 

Edited by numroe

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I'm using the single metal gasket. My squish is at 1.60mm. 63 thou.

Head vol not measured. Sorry. But read on.

My comp was at 245 psi when rings were new.

My fuel is Aus 98 pump.  That's about the same as 94 in the US.

After 51 hrs I have no signs of detonation. Piston crown and head inside looks great. Golden tan and spotless when I checked recently.

Motor runs awesome.

 

I never ran it with the double layer gasket! That would have put the squish at around 1.85 which is way too wide. I knew that (with most/any 2 strokes) a wide squish meant hesitation and fussy jetting. No fun at all.  I know that too tight can mean deto, rough off idle and RPM surging. I thought I'd give it a go with a single gasket, and got lucky.

 

I'm no engine builder! But I think it's pretty simple to get one of these things right. EG does the magic with the porting.  Note that it's not always a case of bolt on and go. Same reason that stock YZ250 motors differ a lot - there seems to be minor tolerance errors in the Yam motor, and EG cannot predict these. So I assume he (and Yam with the stock setup) has to be conservative and error the squish on the wide side, rather than letting it be tight.

1. Get the squish right. By machining the head or changing the cylinder height. Option depends on how high or low your want your ports and how high/low you want your peak torque.

2. Get your head vol right to avoid deto or allow practical starting. 245psi with Aus 98 works. But it's hard to start.

3. Set your spark timing. Retard for less mid hit and broader power.

4. Play with jetting, and pipes. Jetting compared to stock is typically one size smaller on the pilot and main, but keep your half throttle jetting (needle clip) on the rich side to get good progressive and instant roll on torque.

 

Result is an amazingly versatile motor. Torque up steep hills at silly low RPMs in 2nd, or comfortably blast along side 450s out of corners on sand tracks. I use 14/48T sprockets and don't have to shift much more than on my KX450F. 

I'm not complaining, Just trying to get it dialed in. I had my EG295 done late last summer. I bought a damaged cyl for the kit. I only have 5.5hrs on it. I have the timing retarded. Head was cut for pump fuel. FMF Fatty pipe w/ power core 2 silencer. I was dialing in the jetting when it started running like crap. I eventually found a broken reed in my new RAD valve (3hrs on reeds and motor) after checking everything else. Thru the winter I am going thru the motor etc checking things out when I found the 0.071 squish. I assembled it with the dbl head gasket because that is what he sent me. I have some time tomorrow. I will check the squish with a sgl head gasket. I'm sure getting the squish right will made a big difference. I had some detonation under a heavy load.

I planned to get 14/48 gearing too. Glad to hear several people with EG295 are running that gearing with good results.

Have you guys tried the Harris Performance Power valve spring?

Edited by cman962

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I ordered one from him last week.....also replaced my stock reeds with Boyesen pro series and I am anxious to see how it all works with an EG motor. Have to wait until April though to test it out thought......these Alberta winters can drag.

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