What's the hardest bike to work on you ever had?

First gen 4 strokes.  Valves were a nightmare. 

I don't often do large-scale removal of parts, so any difficulty is a temporary thing for me. I will say that my current-gen YZ250 (and every one since 2005,) is really difficult to make carb adjustments on. The aluminum frame is wider right there next to the carb boot than the steel frame was, so tilting, removing, or installing the carburetor is different that what the engineers designed for. If I had two more thousandths of an inch, I swear it would all work!  

The early 2000's KTM four strokes sucked, I worked at a KTM shop, I hated working on them, To pull off the cylinder you had to break the timing chain and press it back together when reassembling the motor, I got pretty good at it but it still sucked.  lol 

Bolts on Suzukis and Kawasakis suck

BSA 750 Rocket 3

My 2000 cr250 seems harder then my 98 cr250

This KTM Projekt from 1988 cost me 1,5 years , Pain and Money to Finish, was a Challenge to work on . 

Honda cub EZ90  you had to have a engineering degree to get the body work off to do any work on them  

2003 Gas Gas EC 300, you needed an extra set of hands to work on it, it was one that required patience.

Easiest thing ever. Line the dots up. You're done. 

2007 to 2012 KTM450 engine with the idler gear and gear driven cams.

Plus every tool you had and some you probably didn’t. Early Husaberg’s were no picnic either. 

My Harley, no contest.

I rebuilt one of those twice. I’m pretty sure the original design didn’t have 3 oil pumps in it. It seemed to be engineered by Rube Goldberg. 

I always wanted one of these 

Any motorcycle with multiple carburetors.

I guess I didn’t mean the process, but more the frequency and people grenading them 

An XT600. Two carbs, sharing a single float bowl. 

I’m in the minority. Owned a 09,10 & still own a 12 CRF450r model. Some of the most durable reliable bikes owned. 
Preferred them over the 05,06 & 08 previous models owned.  
Getting the suspension dialed for you & a Yosh exhaust with a vortex ecu transforms the 09-12 models.  Still one of my favorite gen bikes.  

Xj700x and cbr600f2 are a pain in the ass to work on. Dirt bikes are super easy compared to street bikes.

I'm used to Honda's . The strangest bike to work on for me was the 2012ish KTM's. You had to remove the forks to replace the fork guards. Remove the entire airbox to replace the side numberplates.  So You had to take the bike so far apart to just change the plastic compared to any Japanese bike I had worked on up to that point.  It was a surprise the first one of those I offered to install the plastic kit on for the customer for free when they got plastic and graphics from me. 

All the Japanese bikes were so quick to do compared to that generation KTM. I ended up doing so many graphics kits on those bikes that I could install a full graphic kit wrinkle and bubble free in 25-30 minutes total after a while.    

2003 KTM450 exc. Hands down. 

Husky te610 was a pain lol. 

What gen of Austrian four strokes is it where you have to loosen the subframe and remove the rear shock in order to get the exhaust header off?? 

What a shit idea! All it needed was a 1” shorter header and a 1” longer silencer. 

I have 2 of the '00 CR250's. The struggle to get the intake boot around the carb is real...

Anything with a chain in the engine. 

I hated working on mine. 
Even for changing brake pads.

Was going to post this as well. What a pain. 

This and its big brother the PC800 ….. but look at the trunk!

Gold Wings are another one. Changing the rear tire and doing carb clean was challenging.