Year differences

[Mark911]

Just picked up a back-up bike from a forum member, an 18 MX. I thought the bikes were identical. However, after working on it for a few days I noted some interesting differences between my 17 MX.
1) The 4CS forks are about 1/2 inch longer.
2) The throttle is substantially faster, I'd say a good 15-20 degrees.
3) The water pump is WAY more silent.
4) The cogging feels significantly less just pushing the bike around and oiling the chain.

My 17 was a very early S/N, so 1 & 2 I'm not too surprised about. The water pump, anyone's guess. However, the cogging was a big surprise. It not the rear wheel or chain, I would think it's either a motor change (magnets) or a primary drive ratio thing. I doubt the system would allow the motor to get so hot it'd affect the magnets, but you never know.

Has anyone else noticed differences between the same models?

 

[querlenker]

I saw different throttles on two 17 bikes. Vin were only 4 difference, one 80 degree and one 60.

I use the same type of Bosch waterpumps in many other projects and can tell you that they are very sensitive to air in the housing. If they run without coolant or with an airbumble inside itself, they sound terrible and the pumping power is reduced significantly. The orientation of the pump is very important for self „de-airing“ the housing, the mounting location on the Alta is not optimal too, it’s so high and those pumps are not able to sug if they run with air inside.

Did you overheat the motor often or very hard? I know motor with demagnetized magnets due to much heat which still can run pretty well, but torque and cogging was reduced (own experiences). On the dirttrack it was not so easy not notice and to say how much was the difference. You could see it on the dyno or on street dragrace as the maximum torque was reduced by a large amount.

 

[Mark911]

I've tried several different methods to expel entrapped air with no change in sound. It's been this loud since day one. I'll try to pull a vacuum on the system and see if that helps. In regards to heat damaged magnets I just bought the bike (used) so I'm not familiar with the motor history. However, I can take it to the dealer and have them look at the logged motor temps.

 

[Trialsman]

There are many changes we may never know that are too subtle. I noticed the same reduced cogging on my new '19 EXR compared to my '17 MX. Some other things I noticed about the new one;
- has a Regina O-ring chain
- The triple clamps, although the same, were made of 7075 not 6061 for about 30% increase in tensile strength.
- the master cylinder boot guard is curved at the top to prevent snagging
- obvious better suspension for single track
I am doing my normal prep of the new bike thing now , but can't wait to ride it.

 

[Philip]

I recently got myself one more MXR, a demo with about 50 hours. It runs noticeably more noisy than my two others, both cogging when pushing and also the whining at speed. I am going to change the oil and see if it becomes quieter. But the range is good and the rims are round.

I didn't look at any of my triple clamp part numbers, but this last MXR has pretty tight and grippy clamps. I had to spread them with screwdrivers in order to push the fork legs in or out.

Now I have 3 almost identical MXRs. I am all set with electric bikes and parts for at least the next 5 years, maybe longer.

 

[Trialsman]

Phillip, I also noticed the new rims were not labeled Warp Nine, so maybe they are Excel?

 

[Philip]

Phillip, I also noticed the new rims were not labeled Warp Nine, so maybe they are Excel?

I doubt. But you can call Warp 9 and ask why no label. They should know.

 

[datadog]

Changes were made at an incredible pace, remember 17 was only the first year.

Dealer laptops will not be able to see data such as motor temps. They can output that info, but they cannot view it.

 

[Mark911]

Changes were made at an incredible pace, remember 17 was only the first year.

You guys must have had a configuration control system, correct? So there must be a "as built" vs "as designed" configuration for every bike produced showing all the outstanding deltas and whether each delta is cause for additional actions.

 

[Josh402]

I've tried several different methods to expel entrapped air with no change in sound. It's been this loud since day one. I'll try to pull a vacuum on the system and see if that helps. In regards to heat damaged magnets I just bought the bike (used) so I'm not familiar with the motor history. However, I can take it to the dealer and have them look at the logged motor temps.

I’d be curious about the motor temps, if that’s possible to read. There’s been a few occasions where the battery on that bike went into thermal limit a few times on 90+ degree summer days at my local sand track as I was getting faster.

You can see the light at the 1:54 mark in my video here. Was in map 3 at that time and didn’t even notice until the end when I stopped for a break.

 

[Mark911]

Josh,
Nice riding, that track looked pretty fun. No, just hitting the thermal limit shouldn't hurt anything, that's why's its there. It would have to have been a freaky situation, like a failure of one or several self protection systems, to cause an overheating condition severe enough to affect the motor magnets and overall performance from that point forward. There's many things Alta could have done to lower the cogging torque, simply increasing the air gap between rotor and stator is one. If there was a change in motor spec for the MXR it's possible the newer version was used everywhere once the original stock was consumed. Once folks start getting into the guts of the motor we'll probably discover the story.

 

[querlenker]

It would have to have been a freaky situation, like a failure of one or several self protection systems, to cause an overheating condition severe enough to affect the motor magnets and overall performance from that point forward. There's many things Alta could have done to lower the cogging torque, simply increasing the air gap between rotor and stator is one.

Increasing the air gap will decrease the Kt of the motor and so the torque at a given maximum phase amps. In certain situations this can make sense in high rpm scenarios as it is some sort of field weakening. It was just a idea because I was thinking that Alta would not change motor geometry during first production runs as it’s a lot of time and money involved in this and I thought they concentrated on other things.

I equipped one bike with several temperature sensors at interesting spots, when we have some better weather here, I will datalog and share some information later.

 

[Judaslefourbe]

Phillip, I also noticed the new rims were not labeled Warp Nine, so maybe they are Excel?

Still Warp 9, but as a "private label"