Gorr 05 YZ144 project is a success

[DEX]

Dex-
For the tires, I kept all of dirtrider mag. articles which showed real weights and went from that. There were some comparable tires w/ similar weights but I've had good luck with the M12/S12 combo. Some tires added 2 lbs over stock.
the aluminum body bolts and titanium bolts take prep and care.
- lightweight chains like the MRDL stretch, I'll go through a few in a season I figure. I was surprised to get a chain lighter than stock though.
- alum. clutch plates wear out faster and contaminate the tranny oil quicker than steels do. I change the oil after every riding day

:

What Dirt rider has Tire weights? Anyone know where I can get some of these stats or if someone has the article maybe they wouldnt mind looking up the weights on a 2 or 3 different tires.
What kind of prep and care is required for the aluminum and titanium bolts? I thought the Quadraalloy coating on the Mettec bolts was supposed to solve the Titanium weakness problems.
Was the MRDL chain the lightest out there I was considering running the RK GB520MXZ3 or the Regina 520 RX3 but hadnt really looked into the EK chains but they are also available to me.
How much faster do the aluminum plates wear out compared to steel.

Was the shorty silencer you used the Titanium FMF one?
Would the standard length R304 Pro Circuit Silencer give any weight savings? You know what is cool is Ricky's custom Carbon Fiber silencer on his RM.

And for things you missed.... do you have a Wiseco forged Clutch basket? I was going to get an aftermarket basket just because I had problems with the durability of the stock one on my 85 but the Wiseco one is also lighter than stock I have heard because it is forged. Also what about aftermarket rims and wheelsets are they lighter than stock?

 

[147leeman]

bclapham- thanks for the tip on the linkage bolts, I expect to be inspecting these important bolts on a regular basis. Luckily, here in Indiana our MX tracks aren't filled with the huge doubles and dangerous whoops. We're still kind of old school MX compared to other states and maybe that will take some of the worry out of the ti axles and linkage bolts being bent or damaged from hard landings.

DEX- I've got about six magazines for you that will help. (I'm at work and can't remember what months) One has the hardpack tires of many brands and they're weights, one with intermediate tires and weights, one with soft terrain tires and weights. Most of the soft terrains were lighter than the rest. They weighed the big bike back tires w/ 19" so the 125's will have lower weights and a slightly smaller difference in weights because they're skinnier. They also have the fronts and since they're the same size, the weights came out exactly to what I weighed them as. As for the other 3 mags I've kept, they have weights of pants, helmets, boots etc.

The aluminum bolts easily strip out or bend. The Ti bolts require some sort of anti-seize so they don't get stuck. I've heard of a few people bending Ti rear axles so I check the important ones so I don't have a disaster. With so many parts changed on my bike, keeping a list of stuff to check / watch is very important.

EK's MRDL has lightening holes drilled to reduce weight and I've seen many works 125's with that chain or a copy. Not sure of chain weights of other models, but O-rings do add considerable weight. The clutch plates have lasted about 4 practice days indoors for me. They were right on the service limit when I changed them last. The shorty silencer is from FMF, but it's not the Titanium one...I couldn't dropped some more weight there and may plan get one. I'm sure Pro Circuits shorty has similar weight loss. Haven't even thought of the clutch basket. Assumed the cast alum. stocker was lighter than the billet ones made, but I'll check into the forged ones weight. This bike comes with Excel rims, I've got some articles saved about after market wheelsets and weights. Excel wheel assemblies only are 1 oz. lighter...couldn't justify that price. Talon / Rad hubs are the same or heavier. Stock spokes are the lightest...Buchanon are 8 oz. heavier per wheel. Heavy tubes are just that, heavy...stock are lightest.

On a side note, the drive train weight was reduced dramatically (clutch plates, 2 sprockets, chain, rear tire, ti sprocket bolts/rotor bolts etc.) and the motor would rev too quickly. Add the 144 kit's power and the gearing definitely needed changed. More to come later....

 

[147leeman]

DEX- Here are some of the magazines I've used so far.


July 2004 Motocross Action.....pant weights, helmet weights,
and boot weights.

July 2001 Dirtrider....boot weights

August 2001 Dirtrider.....hard terrain tires (front and rear) weights + performance

September 2001 Dirtrider......intermediate terrain tires (front and rear) weights + performance

October 2001 Dirtrider.....soft terrain tires (front and rear) weights + performance. All 3 tire shootouts by Dirtrider have many manufacturers like Dunlop, Bridgestone, Michelin, Pirelli, IRC, Maxxis, Metzeler but since it was made in 2001 some newer tires won't be on there like Dunlop's 742 front.

 

[DEX]

No luck, I don't have much of a magazine archive and my oldest Dirt Rider is from 2003 I do have Transworld 2002 Buyers Guide but it just lists the prices of avialable tires.

Anyone know the wieght of the Michelin MS2s, MH2s, Bridgestone 601/602, 401/402, 201/202 or the Dunlop 756 RR, 756, 773, 739? I am trying to decide on a tire brand to run for next year for sand and hardcore mud races I am set on the Pirelli MT 410 but after experience with their intermeadiate tires (tires were only used for practice about 3 hours a day and after about 3 weeks every lug except for the very far side ones sheered right off!) I wont run any of their other tires.

I was leaning towards the Michelin Starcrosses unless the m12s and s12s are way lighter I think the Starcrosses would out perform them. They are the most popular tire in my area by far the only people who dont run these are sponsored by another tire company or are those people who continually replace their worn out tires with the OEM tires. Is it Dunlop tubes stock on the 2005 YZ 125 which you say are the lightest? I will order a couple sets of them for race days and some hardcore heavy duty 10 pounder tubes for practice.

 

[bclapham]

bclapham- thanks for the tip on the linkage bolts, I expect to be inspecting these important bolts on a regular basis. Luckily, here in Indiana our MX tracks aren't filled with the huge doubles and dangerous whoops. We're still kind of old school MX compared to other states and maybe that will take some of the worry out of the ti axles and linkage bolts being bent or damaged from hard landings.

Leeman 2 things-

1. with the Ti bolts, it wasnt from them bending, but rather than stretching- you torque them up and after a shortwhile, they seem to be loose again.

2. i was in Indy just last week, there might be an opportuntity for me there, nothing on the table yet, but i have my fingers crossed! of course, i love the old school tracks so that is music to my ears.

 

[jake949]

have you looked into ceramic main bearings? I see that eric has a stroker crank ready to roll on his web site, you should get it :) ;) . I have been thinking of a few weight saving ideas. but one of them i need to proto type. IF it worked it should save weight and help cooling. but i have to find some parts to butcher and i need to see about laying up some carbon.


Have you drilled out the fins infront of the rads? you know for that ultra factory look.

 

[Rich Rohrich]

Ceramic main bearings are a nice addition in a high rpm engine that runs in super clean conditions like asphalt kart racing. The downside is, introducing even small amounts of dirt into the engine can destroy them quickly, which makes them a really poor choice for a dirt bike. ;)

 

[jake949]

thanks Rich. I thought Eric said they worked good. but i might have been mistaken.

 

[KAWA200'sRule]

How is the mo power porting working out. I thought it wasnt a good idea for 125's? Ideal for 250 and 500's. How is the power delivery? Have any idea on hp?

 

[Rich Rohrich]

thanks Rich. I thought Eric said they worked good. but i might have been mistaken.

They work great in the correct applications. Dirt bikes just aren't one of them. :cool:

 

[SpDyKen]

Thank you, all, for the great information! Having recently returned to the fun of playing in the dirt, I have been contemplating building a lightweight '05 YZ125 woods bike to harrass my big bore buddies with.(they keep encouraging me to ride their KTM 300s & 450s) It's now become a plan. Please continue to update us with your progress. You all have saved me the embarrasment of bothering Eric & Rich with a bunch of elementary questions! Thank you again.

 

[SpDyKen]

By the way, glad I stumbled on your EGFM website, Eric. I appreciate the info. there, bought the book, and found DRN. What a find! Probably haven't seen you since the first (my only) Santa Fe Speedway speedway race. Was that '79 or "80? Again, I appreciate all you have and continue to do for the sport (business) and us all! I'm enjoying catching up on some of it here. Keep up the great work and keep those chips and shavings flying! KW

 

[Jeff Howe]

If anybody has info on that Racers Edge quick throttle let me know, I want one for the same reason.

 

[Lonewolf]

On the yz144, do you have to do any mods. to the bottom end, or can you just send the cyl. and head? Also, do you think the stock pipe and silencer is ok to use with the 144?

 

[steve125]

On the yz144, do you have to do any mods. to the bottom end, or can you just send the cyl. and head? Also, do you think the stock pipe and silencer is ok to use with the 144?

On the 05 even more so than the previous YZ 125 models. The front of the main engine cases need to be relieved 1-2 mm or the piston will hit. This can be easily done after taping off the crankshaft area, with an air die grinder. I usually follow this up with a pre-mix flush of the lower end, as its just about impossible to not have some chips enter into the lower crankcases.

The stock pipe and silencer while not ideal, will work fine with the 144 kit.

 

[JustinC]

If I decide to go with the 144 on my yz can I ever change it back to a 125 again, or will the mods that have to be done to the bottom end prevent this? What about the power valve does that need modified as well?

 

[Eric Gorr]

The head and powervalve can be used but you'll lose a lot oflow end.

 

[Eric Gorr]

SpyDyKen,
Robert Blalock and Brian Browning are 2 of my customers in the Atlanta area who are running 144s on 05YZ125s in enduros. They are both 40+ and switched from 250s to the 125 for the handling and weight savings. Look them up at the races. Robert is a product developer and tester for Yamaha.

Only one track has a track of clay, Santa Fe Santa Fe! Rich and I had a lot of fun at that track, we tested our proto low CG bike there is 1982. The track is gone now, the space is filled with million dollar houses. So much history, so few brain cells left to remember it all!

 

[JustinC]

Thanks for the responce Eric. I think I will send in my motor for the 144 kit this up coming winter, I don't want amny down time during the summer.

 

[JustinC]

Eric, I also wanted to ask about 144 maintence, are top and bottom end rebuild intervals much different than a standard 125? If I decide to go with the 144 I would probably have you port it Mo Better if that makes a difference.

 

[Phillip Green]

Wow!

I'm going to purchase a 2005 YZ125 soon and plan to have Eric do the big bore on it. Can't wait to see what you did to take extra pounds out of the already light machine!