125-200cc So you want to convert to a 165

It is mostly a pipe/carb selection.

Pipes and carbs help but they only go so far. The problem with the 165 as I see it is the 125 porting. If I were to do the 165 I would send the cylinder off to Eric Gorr for a decent porting job. That's why it hits so hard off the bottom and wheezes on the top. Just like my Bultaco Alpina!

That isn't accurate at all Doug. If you rode my current bike you would crap yourself. It will run circles around your "144" everywhere. The bike you rode had very conservative porting(exhaust) and tuning. It was a very nice trail bike and is a great saw bike.

I also have to say at this point I have "fixed" 6 botched jobs by your porting guy. I know we all make mistakes but I was stunned by the lack of attention to detail in the kits I worked on. This is after how many years in the business? He may have some good ideas and designs but execution was marginal. I learn a little everyday and stand behind everything I do, mistakes and all. The 165 isn't the best motor for everyone but it is for me and has gained amazing flexibility with learned experience(yes, I have made my share of mistakes). I would like the next time I am in your area we strap it on and find out which motor really rules. Yes, I will gladly spot you the 50#'s difference in weight between riders.

Not a very fair decription I must say !!
Walts work is just superb LONG LIVE THE 165

Sorry, Walt. Eric has always done a great job for me over many years and many different motors. He is the only man I know who could make the crappy Yamaha YZ490 rip without pinging or seizing!

You must have one heck of a fast 144 . I had a 144 with high compression running on race fuel and it was fast and fun no doubt but...my WB165 would run cicrles around it, eat it's lunch, and take a nap while the 144 tried to catch up. A friend has a 2009 Eric Gore YZ 144 and my 144 Husky would easily out run it with me spotting him 30lbs of fat; I mean muscle. I'm not say'n your EG144 isn't a good runner but I have serious doubts it comes close to a WB165. There is no "weezing on the top of my 165 and no hard hit off the bottom. Just crazy power from the bottom to the top for 165cc IMHO.

Yeah I almost looped mine on a 4th gear pinned double the first time I took my 165 to our MX track ! This thing got my attention real quick after that. I was use to my 2010 TC TC250. I haven't put mine in the sand yet just hard pack red clay but can't wait to get to a sand track.

How do you think the 165 would go with a fatty 125 pipe. Would it still crap on a 144?

I had a 125 Fatty on my 144 and put it back on my 165. I would say the 165 still had the 144 covered but not by much on top with the 125 fatty. I could tell it was being held back in the upper RPM's and thought it was the 125 pipe. When I bolted on the KTM 200 modded Fatty pipe she woke up big time. My next step was the SmartCarb which smoothed out the entire RPM band and gave it more power everywhere. I wouldn't do a 165 without a 200 pipe unless you just ride in the low-mid rpm ranges.

I havent ridden the 165 but I think it all depends on what sort of riding you do. Most 125, 144 and 165s make similar hp but at differnt RPMs . I am a big fan of the 125 for the top end but it can be PITA at times. The 144 in standard form lacks some of the 125 top end and also needs some port work to raise the port timing .
Some 144 kits are bore and stroke and work better - check out Max power 144 kits.

I have the 144 going very hard but do not think porting work is money well spent . If i was to get anyone to do it it would be Walt( if he'd do it )
We are lucky to have guys like Walt . I spoke to a local mechanic about porting and didnt want to touch it .
Having ridden and flogged the CR144 around a sandy mx track I was wanting more mid range power.

I am currently going for the 165 as I think it will be make up for any loss in top end by having the power where I need it the most - around 6000- 8000 rpm.
The 165 will also help me to put to shame some of my mates on the rocky hills we ride.

For most of us a bore and stroke version of the 165 would be and are too expensive .

No problem Doug! You just need to realize that the 165 you rode had an exhaust port that was 3mm lower than what I build, the power valves were raised farther than normal to enhance the mid and reduce hit, and the timing was significantly advanced to promote the bottom/mid. All those things together made a motor that had gobs of bottom/mid with very little hit when the power valves opened with top end reduced. All fed by a carb.....Old tech.

I am sure that Eric Gore does fine work and has very good mods but he also has had employees that don't necessarily produce quality work. It is the problem with getting so large that you have to trust employees to do what you would normally like to do yourself. Sometimes they are hungover or pissed off or both. I have had thousands of employees in my life and know all about the issues of delegating, being let down, and scrambling to control the damage. You can't possibly know what an individual is going through in the rest of his life that is going to affect the product.

I have never had a single problem with any work done by Eric Gorr or his employees. Just this year I sent off a cylinder from my well modified (2007 SSS Racetech forks and YZ450 gears) 2001 YZ250 to Eric. The problem was the motocross porting made it hit very hard early in the powerband. Great for track riding but my right arm would really pump up in a tight rock section because I would have to be so careful in feeding in the throttle. He decked the cylinder and modified the porting so that I don't even need a flywheel weight anymore. Super smooth off the bottom and a nice mid range kick that works great in the woods! As far as the WB165 al I know is what I rode. If that was different from what others have purchased well, I had no way of knowing that. I am an engineer and everything I do is subject to several layers of critical review. I tell it like it is.

I am a 125 guy, I prefer the 125 for my riding style.

That said I have ridden 5-6 of he 144's and 3 of the 165's, all 3 of the 165's were on the same day and all tuned very differently. The high compression race gas running 165 was insane fast. I also rode it back to back with a 2012 KTM200xcw that day and it gave up nothing at all power wise to the 200. It was nuts, I really want to ride that bike on an MX track it is a 250f killer, none of the 144's were anywhere close not even in the ballpark. That includes the same bike as a 144 a few months earlier.

There is an non engineers opinion, I am a machinist though so I have an eye for detail and have to take what the engineers give me and make it a reality. Sometimes that is not too easy.

Later,

As I stated, I am sure EG has some great mods. That doesn't explain the Husky EG 144's that ate their top ends all within 20 hours. All from the ring catching the un-chamfered exhaust port. The excessive hit and weak bottom/mid from the power valves not being returned to at least the stock height when lowered by machining to the new bore. So I am glad you have a successful relationship but there have been issues and they are all directly related to quality control.

I fail to see how you can claim critical review from spending less than 5 minutes on a bike. Mostly spent on a fire road. Sorry Doug but if you had tackled a single gnarly section of trail that day on that bike you would have seen its value. I don't want to dump on you but you keep making judgements on the viability of the kit from incomplete information.

It would be great to dyno all three(125,144,165) at the same time and post the numbers.
In my humble opinion it seems a lot of people are hung up focusing on HP numbers and not taking into account most riders can't wick the power all three bikes offer anyway.