Posted September 30, 2006 - 04:20 PM
Does anyone here have a YZ 144? Any companies I should specifically avoid? Any companies that you would recomend?
Posted September 30, 2006 - 06:09 PM
Posted September 30, 2006 - 06:44 PM
Posted October 01, 2006 - 07:25 AM
Posted October 01, 2006 - 07:26 AM
Posted October 01, 2006 - 03:44 PM
i dont know how much it cost for the bore.. ill check my receipt.. cause i walked out of the dealer spending about 1500 for just about an entire new engine... bearings, gaskets, piston, wrings, tranny, shifting forks, bore out.. etc.. i would say more than a hundred.. i konw you can get a 2mm bore for like 40 bucks.. ill give you name of it when i think of it...
Posted October 03, 2006 - 10:13 AM
I think the problems with the exhaust ports you're talking about are where the porter has to widen them considerably. The piston ring will tend to bluge out into the port slightly as it goes by, over time it causes the ring to wear faster then normal. Hence the reason you see tuners suggest replacing the ring(s) sooner on overbores. The same thing can apply to the transfer ports...
Posted October 04, 2006 - 07:17 AM
I think you'll be disappointed if you think a YZ144 is going to smoke a 250f. You will have a bit more peak power (and only a bit because 250fs are making more and more power each year, just look at the 250SXF) but in terms of area under the curve the 250f still be superior, and peak power means very little to the average guy riding on slippy dirt. It will certainly go some way to evening things up, just don't expect to be blown away.
This is actually a pretty accurate depiction of the situation. The 125, if built properly can not only make a bit more peak hp, but can be made to have several more peak hp, but that does not necessarily equate to good rideability for most people.
More peak hp and lowered rideability certainly does not equate to a more competitive bike in most cases for most riders (maybe the special few that can keep it in the small zone). There is no cheap fix to the 125/250F battle. I think any 144cc conversion needs to be a well thought out and integrated attack on power band width and torque characteristics to make it more like the 250F. The reality is that the 125's still spin up faster and have a decided advantage in many areas...torque and hp delivery width is the true weak point though.
My philosophy is that you don't worry so much about peak hp, but focus on using the mods to get the modified 125 to the best it can be on power band width, torque and hp delivery characteristics for your use/want.
With that said, even if you double the power band width...you still can't match the 250F for width, but you still get the other benefits of the 125 (weight, faster revving, little gyroscopic effecting handling, less expensive maintenance, ease of maintenance, etc)
The best 144 is one that has been given planning, professional installation, and a integrated system (BB piston, head mods, porting, pipe, reeds/reed block, carburation, etc) to meet your goals.
Posted October 04, 2006 - 10:25 AM
1. Stock YZ 125: 29-30hp 15-16 lbft torque
2. YZ 144, FMF Factory Fatty, Shorty Silencer, VForce 3, Extensive Power valve modification along with port configuration and head work.
37 hp 20 lbft torgue, pulls past 12,000.
Engine builder tuned in chasis and said would pull 3rd gear starts with 48t rear sprocket and he weighs 165lb.
Posted October 04, 2006 - 02:07 PM
Try some well thought out gearing changes to maximize delivery width as it revs quicker still. Make it deliver the forward momentum like a 250F does. Try a light FWW and/or gearing like 14/50.