Cutting Power Bands

backtire
Profile picture for user backtire
Posts
11
Joined
7/12/2014
Location
Julian, NC US
backtire
Edited Date/Time 6/19/2015 2:24am
Hi All , haven't been on in a while But, Traded the two bikes I had for a 97 Honda 2 stroke water cooled dirt bike that I know nothing about and don't believe anyone around here does either , Ant way This engine had been rebuilt then blew the head gasket scared the cyl. so with new Wiseco piston .080 over had it bored , they did nt cut the power bands back / the person working on it with me has some knowledge but does not seem to know how much to cut the power bans back or how to check them for rightness . Can some one please Help , My 16 yr. old is bitting my bit here is a pic of the bike I don't know what style the bike is and have some Goodies to put on it after we get this straightened out .

Sorry I don't have a better pic.
|
MOTODAD422
Profile picture for user MOTODAD422
Posts
430
Joined
9/26/2008
Location
Easton, PA US
MOTODAD422 6/7/2015 8:59am
6/7/2015 8:59am
Don't cut the stock band,just install a purple power band and she will rip.
downard254
Profile picture for user downard254
Posts
4055
Joined
12/10/2012
Location
Bremen, OH US
downard254 6/7/2015 9:08am
6/7/2015 9:08am Edited Date/Time 6/7/2015 9:09am
If you can't afford the purple power ban, they can be cut, but you have to be very careful about it, and there are a few tips to get just a little more grunt out of her. I've seen people cut them with hack saws and just file the edges smooth, they will function, but you will limit yourself to it's full potential. I remember someone putting a video on YouTube showing a cutting method that gave the bike 3 more HP and engine response was like fuel injection. I think they cut the edge off on approximately a 3 degree angle, then used a Dremmel tool with a red ruby 45 degree taper stone, and polished the edge to a mirror like finish. This smoothed it's action and and brought the power on quicker and stronger. Like I said, I think I saw the video on YouTube, but you might be able to google it.

Edit: By the way, I'm digging the frame modification that was made to that '97. Lucky find.
Matt Fisher
Profile picture for user Matt Fisher
Posts
3948
Joined
4/1/2008
Location
Visalia, CA US
Fantasy
1177th
Matt Fisher 6/7/2015 10:36am
6/7/2015 10:36am
downard254 wrote:
If you can't afford the purple power ban, they can be cut, but you have to be very careful about it, and there are a few...
If you can't afford the purple power ban, they can be cut, but you have to be very careful about it, and there are a few tips to get just a little more grunt out of her. I've seen people cut them with hack saws and just file the edges smooth, they will function, but you will limit yourself to it's full potential. I remember someone putting a video on YouTube showing a cutting method that gave the bike 3 more HP and engine response was like fuel injection. I think they cut the edge off on approximately a 3 degree angle, then used a Dremmel tool with a red ruby 45 degree taper stone, and polished the edge to a mirror like finish. This smoothed it's action and and brought the power on quicker and stronger. Like I said, I think I saw the video on YouTube, but you might be able to google it.

Edit: By the way, I'm digging the frame modification that was made to that '97. Lucky find.
In 97 the 125 frame was steel. The 250 got the industrial strength aluminum frame.
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 6/7/2015 11:09am
6/7/2015 11:09am
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make contact with the piston or rings.

Paw Paw

The Shop

See All »
respect_the_beast 6/7/2015 1:26pm
6/7/2015 1:26pm
I've always just used scissors for my power bands. The factory teams use Kevlar ones and J-law said you can't use scissors on those. #bikelyfe
backtire
Profile picture for user backtire
Posts
11
Joined
7/12/2014
Location
Julian, NC US
backtire 6/7/2015 2:51pm
6/7/2015 2:51pm
Paw Paw 271 wrote:
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make...
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make contact with the piston or rings.

Paw Paw
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come in and out of the cylinder where the the ports are , Sorry I don't have a picture right now , they are controlled by a gearing mecaniseim on the outside of the jug ( 2 Stroke ) water cooled Honda ,,,Yhanks for the replies but I have never seen a head band in a engine ? I do trust some of your opinions ,, Woohoo
pete24
Profile picture for user pete24
Posts
2733
Joined
10/20/2011
Location
Marlborough, MA US
pete24 6/7/2015 3:18pm
6/7/2015 3:18pm
nice chain buffer
MR. X
Profile picture for user MR. X
Posts
6917
Joined
6/24/2010
Location
North Tonawanda, NY US
MR. X 6/7/2015 3:23pm
6/7/2015 3:23pm
backtire wrote:
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come...
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come in and out of the cylinder where the the ports are , Sorry I don't have a picture right now , they are controlled by a gearing mecaniseim on the outside of the jug ( 2 Stroke ) water cooled Honda ,,,Yhanks for the replies but I have never seen a head band in a engine ? I do trust some of your opinions ,, Woohoo
Those are the power vales , i went .08 over on my 125 , i just used a hand grinder to put the clearance on them to remove the interferance.
downard254
Profile picture for user downard254
Posts
4055
Joined
12/10/2012
Location
Bremen, OH US
downard254 6/7/2015 5:39pm
6/7/2015 5:39pm
downard254 wrote:
If you can't afford the purple power ban, they can be cut, but you have to be very careful about it, and there are a few...
If you can't afford the purple power ban, they can be cut, but you have to be very careful about it, and there are a few tips to get just a little more grunt out of her. I've seen people cut them with hack saws and just file the edges smooth, they will function, but you will limit yourself to it's full potential. I remember someone putting a video on YouTube showing a cutting method that gave the bike 3 more HP and engine response was like fuel injection. I think they cut the edge off on approximately a 3 degree angle, then used a Dremmel tool with a red ruby 45 degree taper stone, and polished the edge to a mirror like finish. This smoothed it's action and and brought the power on quicker and stronger. Like I said, I think I saw the video on YouTube, but you might be able to google it.

Edit: By the way, I'm digging the frame modification that was made to that '97. Lucky find.
Matt Fisher wrote:
In 97 the 125 frame was steel. The 250 got the industrial strength aluminum frame.
Sarcasm
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 6/7/2015 8:44pm
6/7/2015 8:44pm
Paw Paw 271 wrote:
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make...
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make contact with the piston or rings.

Paw Paw
backtire wrote:
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come...
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come in and out of the cylinder where the the ports are , Sorry I don't have a picture right now , they are controlled by a gearing mecaniseim on the outside of the jug ( 2 Stroke ) water cooled Honda ,,,Yhanks for the replies but I have never seen a head band in a engine ? I do trust some of your opinions ,, Woohoo
Yes that is the power valves. They will have to be fitted to the new bore or it will screw up the piston and rings.

Also as an FYI..........Talk about "Power Bands" will always get you a lot of Sarcasm as there is no such actual part.

Paw Paw
backtire
Profile picture for user backtire
Posts
11
Joined
7/12/2014
Location
Julian, NC US
backtire 6/8/2015 6:00am
6/8/2015 6:00am
Well that explains a lot wondered why I was getting some goofy answers .08 on a .080 bore (I think I got that right ) Is it a real pain to take these valves out and do that and get them back in right of coarse ? is there some timing involved ? Thanks Guys you will have made my son a happy rider again. Man I still miss my 77 250 YZ I see it setting there waiting and had a lot of good times on that bike Evil
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 6/8/2015 5:05pm
6/8/2015 5:05pm
A service manual will be a big help for about anything on this bike. It's not a hard job but you can screw it up if you don't have a good guide like a manual. They are cheep on line.

Paw Paw
backtire
Profile picture for user backtire
Posts
11
Joined
7/12/2014
Location
Julian, NC US
backtire 6/9/2015 10:31am
6/9/2015 10:31am
I will get a manual Thanks for all your Help I will post some pics. when wee get it straightened out . Eric Smile
mark_swart
Profile picture for user mark_swart
Posts
2410
Joined
11/2/2011
Location
Chapin, SC US
mark_swart 6/10/2015 7:29pm
6/10/2015 7:29pm
Uhh.. don't CR 125s have nikasil cylinder liners? Unless somebody has put in a sleeve, that thing is going to melt down in short order.

backtire you need to confirm if it has a steel sleeve or not before you run it.
cwtoyota
Profile picture for user cwtoyota
Posts
1934
Joined
3/11/2013
Location
Tacoma, WA US
cwtoyota 6/10/2015 11:16pm
6/10/2015 11:16pm
A typical owners manual or repair manual will not cover the issues you seem to have.

If you need to have your cylinder bored oversize, avoid the steel sleeves. Have it re-plated by a competent shop like Powerseal USA or Millenium Chrome.

If you already have a steel sleeve, make sure it has been honed to the correct size for the piston you are using. The clearance is a crucial measurement.

The shop that bored the cylinder should have done the work on the power-valves when they did the bore work. It will be obvious, they should not stick out into the cylinder bore.

backtire
Profile picture for user backtire
Posts
11
Joined
7/12/2014
Location
Julian, NC US
backtire 6/16/2015 7:23am
6/16/2015 7:23am
We got them cut back .008 and seems to be working ok for now , although not broken in good yet , warmed it up and changed the oil ( was told 10-40W ) was ok any way when we drained it was over filled and had a lot of metal fragments in it , I guess were it was were the lower end was rebuilt before I got it and refreshed the top end ? needs a few things like a front tire (were do you guys recommend getting one from e- bay has this http://www.ebay.com/itm/80-100-21-Full-Bore-USA-M37-MX-Intermediate-Fro… seat cover and some other odds and ends . I feel sure it was steel bore and the shop final told me it was there first 2 cycle bore and they wanted to charge me extra for a half A@@ JOB any way here it is with my 16 smiling son on it .

Pit Row

See All »
MXtoXS
Profile picture for user MXtoXS
Posts
104
Joined
12/21/2013
Location
Grand Junction, CO US
MXtoXS 6/17/2015 6:55pm
6/17/2015 6:55pm
The oil in the bottom is not shared with the reciprocating asmy. Piston/crank lube is from the gas/oil mix in the gas tank.
markit
Profile picture for user markit
Posts
2638
Joined
1/10/2013
Location
Bogalusa, LA US
markit 6/19/2015 2:24am
6/19/2015 2:24am
Paw Paw 271 wrote:
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make...
Are you talking about the cutting of the exhaust valves? If so they have to match the new size cylinder bore so as to not make contact with the piston or rings.

Paw Paw
backtire wrote:
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come...
Paw Paw am not sure I was told The two pieces of metal that look like a part of a horse shoe or so that come in and out of the cylinder where the the ports are , Sorry I don't have a picture right now , they are controlled by a gearing mecaniseim on the outside of the jug ( 2 Stroke ) water cooled Honda ,,,Yhanks for the replies but I have never seen a head band in a engine ? I do trust some of your opinions ,, Woohoo
Paw Paw 271 wrote:
Yes that is the power valves. They will have to be fitted to the new bore or it will screw up the piston and rings. Also...
Yes that is the power valves. They will have to be fitted to the new bore or it will screw up the piston and rings.

Also as an FYI..........Talk about "Power Bands" will always get you a lot of Sarcasm as there is no such actual part.

Paw Paw
Take that back, my 200 has a power band in every gear. Smile

Post a reply to: Cutting Power Bands