HPBikes 300

[Bruce372]

wow!

 

sorry dude, i hope at least you got a refund for the labor.

[BRM]

Looking into the exhaust port

📎ImageUploadedByThumper Talk1414632120.353181.jpg

Not much work done in there. What porting did you have?

[BRM]

I pulled my EG 295 down last week and found bits of the power valve assembly had broken with some going through the engine.

Dents in the top of the piston and under the head and some scores in the cylinder.

Ultimately it needs a replate but I cleaned it up and slapped a new piston and rings in it so it lasts another month of riding then I will strip it and have

it replated.

 

In the mean time I have orders an Athena 294 BB and am having it ported. I will carry it back from Australia when I go on holidays.

Can't wait to try that.

[too much]

I asked for a motor that would climb mountain boulder shoots but still scream when we hit the dunes.

I'm still undecided if it does any of that better than my stock 250.

I'm taking the jug to another guy tomorrow to get another opinion.

[too much]

BRM, does your Gorr piston have the same part number as mine?

I'm curious how the Athena piston compares. 

If the pin height is moved maybe the jug wouldn't need to be cut and the exhaust port wouldn't have the issue mine has.

[homo erectus]

If any of you with Eric's 295 ever have your jug off could you measure the heights of the transfer ports and the exhaust port.

I went to Split Second today, he measured it up and there is nothing that can be done to this jug.

According to this engine builder the transfer ports need to be raised 2mm but with the current porting he can not do anything more.

He suggested I cut the race gas head for .050 squish and the pump gas head for .060 and run it.

The cases are split, I've decided to go with the YZ 1,2 and WR 3,4,5 as I don't need the super steep WR first gear.

Hopefully there's no snow on the ground for next weekend! 

 

I measured from the o-ring surface of the jug looking down into the cylinder.

Top of the exhaust port-37.3mm        

Bottom of the exhaust port-74.3mm

Top of the transfers-59.4mm

Bottom of the transfers-74.9mm

Top of the intake port-84.9mm

Bottom of the intake port-122.1mm

Total length of the jug from the o-ring surface to the base gasket surface-121.2mm

 

The builder that looked at it yesterday made a comment about the exhaust port being too low. The base of the jug has been milled 2mm which I assume has to be done to get the piston in the right spot as it still isn't zero deck height but if we took more off the jug it would make the exhaust worse. He talked a lot of porting talk that I don't understand, blow down, etc. He told me to find a new jug, head and let him have a go at it. It would be a $1000 all over again.

I'll take a pic of the exhaust port looking into the cylinder later today.

 

If your port measurements are correct your exhaust port (you didn't specify sub ex. or main ex.) is not too low, stock yz sub ex. opens first at 40mm with the main at 40.5mm so yours is raised 2.7mm. If your cylinder was indeed decked 2mm it is the same as just .7mm higher than stock.

 

Your problem is in the intake port heights. First your transfer ports are set at 59.4 whereas stock is 59, remove the -2 and it's like being at 61.4 or 2.4mm lower than stock. You show the intake port(I assume the rear boost port) at 84.9 when stock is 58 so that is 28.9mm lower than the stock port height(including the -2). It appears that the intake ports weren't reset after the cylinder was bored out to 72mm

[highmarker]

Did you get the top edge of piston to top of jug at tdc, stroke, rod length?

[too much]

Bottom ends back together with WR 3rd, 4th and 5th. I'll measure piston deck height tonight if I assemble the top end.

The stroke and rod length should be stock but it is a Hot Rods crank and rod.

[too much]

I went to see the other builder today. He says the same thing, with what's been done to this jug nothing can be done to fix the issues. Transfer ports need raised 2mm and there is no room to safely do so. He said there is very little porting done to this jug. Both guys I've seen can not understand why a builder would market this 295 with that piston. A custom piston is needed to do this correctly.

He has a MaxRPM 285 piston there so we did a quick check on the pin heights.

[too much]

He also just ported an ESR 325 as the owner had it dyno'd and thought it was a turd stock. He didn't tell me numbers but said the owner is very happy with the ported 325 and there is lots of room for work with the way the kit comes.

He said a ported 325 would be miles better than what I have right now for the power style I'm looking for.

This may be my next step.

[GCannon]

Please help me understand as I am confused after reading all this?

 

You sent your cylinder to Derek at HP for bore and porting? and what you got back performed poorly including the Cylinder Head squish?

 

You talked to Derek and now there is nothing he can do for you?

And now you are going to start over with an new cylinder kit?

 

The reason I ask is that I am preparing to build a 144 for the boy to race enduro's  Pump gas and Low RPM power will be part of the design.  (yes I know its  a144)

[too much]

The kit goes ok, it's just not what everyone here says about 295's.

Derek offered to check the clearances if I sent it back.

I told him I'd take a new piston instead of his labour on the advice of a guy I really respect locally that the 2 builders I've gone and talked to could do just as good or a better job of setting up a 295 for me.

Derek had his chance, there's little port work, squish is way off, parts came back broken, took twice the quoted time.

Would you send it back?

I read reports on the 144's. Guys say his are the best.

That's why I went there.

Monk's 250 rips from what he says. I read Monk's posts. He rides and from what I've read he rides pretty hard. If he says Derek's 250 is awesome, I believe him.

This 295 isn't right, the 2 builders here that measured it up shake their heads. It's all wrong and it sounds like the piston and what he had to do to make this generic Wiseco piston work cause the problem.

Basically I live with this kit or start fresh. With this not coming out with what I was looking for my only choice is to try something new.

I was hesitant on the ESR325 but I feel better after talking to the builder I talked to today.

[BRM]

BRM, does your Gorr piston have the same part number as mine?

I'm curious how the Athena piston compares. 

If the pin height is moved maybe the jug wouldn't need to be cut and the exhaust port wouldn't have the issue mine has.

Piston Part number is the same.

I'm not just doing an Athena piston, I will be doing the full Athena 300 kit.

I'm sending to a respected tuner in Melbourne to sort it before it comes to me.

Should have it early next month when my boy brings it across for me.

 

Also,Too Much, from what you have stated you want out of the motor, I would suggest you go with Mid-top porting and a big FWW.

The mid-top porting leaves it nice and smooth down low for the rock climbing and the top end sings out in the open

[Hans Schmid]

The kit goes ok, it's just not what everyone here says about 295's.

Derek offered to check the clearances if I sent it back.

I told him I'd take a new piston instead of his labour on the advice of a guy I really respect locally that the 2 builders I've gone and talked to could do just as good or a better job of setting up a 295 for me.

Derek had his chance, there's little port work, squish is way off, parts came back broken, took twice the quoted time.

Would you send it back?

I read reports on the 144's. Guys say his are the best.

That's why I went there.

Monk's 250 rips from what he says. I read Monk's posts. He rides and from what I've read he rides pretty hard. If he says Derek's 250 is awesome, I believe him.

This 295 isn't right, the 2 builders here that measured it up shake their heads. It's all wrong and it sounds like the piston and what he had to do to make this generic Wiseco piston work cause the problem.

Basically I live with this kit or start fresh. With this not coming out with what I was looking for my only choice is to try something new.

I was hesitant on the ESR325 but I feel better after talking to the builder I talked to today.

 

I understand your frustration, going through the BS with my powervalve was painful. To the point where I was going to buy a new bike.....

 

Sorry to here about things with Harris, I was out for a ride today and the bike was a hoot to ride! The power is just so dam awesome to ride....

[too much]

BRM, I think your right on that style of porting.

Can you compare the Athena piston to the Wiseco when you get it and report?

I'm very interested to see how they built that kit.

[cman962]

Too much, I have a thought.to save your cylinder.

Why can't you have a 2mm thick shim (minus an extra base gasket to go between the cyl base and the shim) made to match the shape of the cylinder base. This would put the 2mm that was cut off the deck back and get the porting up where it should be or in tbe range where someone can port it.

The top of the cylinder might need cut down like Eric Gore does. And of course the head would need to be cut to get the squish and volume correct.

Any decent machinist could make a shim in short order with a basic manual mill by tracing a base gasket on a piece of alum sheeting and milling it out.

[too much]

We thought of that but the final decision was it's not worth doing to this cylinder now.

Both builders suggest I either sell it and start fresh or run it and it is what it is.

I'm mulling it over right now.

ESR's kit looks like a good deal at $850, room for a porter to make it the way you want it.

I need to read more on everyone's experiences with it before I make the call.

The MaxRPM 285 might be the hot ticket as well.

The piston looks to be designed for a YZ cylinder.

The Wiseco I have right now is listed for many applications to build a 300.

http://www.wiseco.com/ProductDetail.aspx?ItemID=878M07200&ModelID=458&ModelYear=2005&AppID=49550

[Hans Schmid]

Here was a pull on my 250, super smooth all the way through...

Let me know what you want to do with your cylinder and such, I would be interested...

Edited November 1, 2014 by Monk

[smv ryder]

Here was a pull on my 250, super smooth all the way through...

Let me know what you want to do with your cylinder and such, I would be interested...

So roughly 42hp at the wheels for a YZ 250 smoker? Sounds and looks like an amazing power plant. Very linear power IMO

[too much]

MaxRPM's 285

http://www.maxrpms.com/yz-285-big-bore/

They state the issues with the 295 on their site.